Your dryer will need the full diameter to be able to exhaust its air easily, so yes, you should either replace it, or attempt the fix below.
The diameter is a bit hard to see, but if it's large enough to stick your fist in you can easily manually uncrumple it. There might be a few sharp edges inside, so just in case you should wear simple workman's / gardening gloves. Carefully opening your fist at increasing depths should allow air to pass through again.
The duct is fixed to the pipe with aluminium tape, so afterward you'll need either a roll of that or a duct clamp. It does need to be secured, or it might come off again over time.
It is held on by duct tape or metal foil tape (metal foil preferred) and/or a simple clamp with one screw. Temporary fix is to remove from wall, clean out lint, push back into shape and reattach. Do not reuse the tape - it won't hold as well. If you can't get it totally off, don't worry about it - just add a fresh layer on top.
Permanent fix is to replace with a length of smooth solid steel duct and (typically) two elbows, one at the wall and one at the dryer.
Flexible duct has an advantage if you move the dryer frequently (most people don't) or in some cases if the ductwork has a complicated path (which is best avoided).
Both other answers are good, but there's another solution.
The vent is an accordion. Not a good one, so you can really only lengthen it. Shortening it take a bit of skill, patience, time, and luck.
But you have loads of spare vent to use, as can be seen in the top picture of the compressed vent. If you can't reopen the crushed section or it pops a seam (which can happen pretty easily), you can just cut off the crushed section and pull out the vent to match the missing length.
Cutting the vent can be a bit tricky, but totally doable with basic tools. A tin snips, aviation shears/side cutters/nippers*, or some fairly hefty scissors can do the job.
You may want to wear gloves, since the vent can be fairly sharp. Losing grip and sliding your hand across the cut edge is an almost guaranteed bloody and ragged gash. My hand just hurts thinking about it.
*There's a lot of names for the same types of tool depending on location, so I just named a few to give a rough idea of what the OP is looking for. Not all regional or official names are for things that would work well, even if they have a possibility to work. And there are other similar tools that would work just as well.
While you have it disconnected
You might want to inspect the inside of your pipe to make sure it's not getting clogged. With the crimped section you have, the flow isn't as it should be, so there could be a lint buildup happening. Lint can build up in these over time anyway, so it's not a bad idea to take a look inside and see if you need to clean it out. A quick swipe with a vacuum hose or a rag on a stick can clean most of it out pretty easily, if it's not too bad.
If it has a serious amount of lint, you might just want to replace the vent, rather than trying to clean it out. They are relatively inexpensive and should be easily found at any hardware or home improvement store. Most appliance stores should have them, too.
A clogged vent can not only reduce the ability of your dryer to dry your clothes, but, in extreme cases, can ignite the lint and cause a house fire. The lint filter in your dryer is good, but not perfect, so we all need to inspect these vents every so often for blockages.
On a side note, there are ventless dryers. They are gaining popularity in the EU, but are not common in the US. From what I read, they are also lower capacity and more expensive, due to being relatively new designs. (I only know about these dryers because I've been looking for a new one.)