Twist or distortion in a prawn's back (4)
I believe the answer is:
warp
This clue could be a double definition.
'twist' is the first definition.
(I've seen this in another clue)
'distortion in a prawn's back' is the second definition.
'warp' can be an answer for 'distortion' (warp is a kind of distortion). I am not sure about the 'in a prawn's back' bit.
'or' is the link.
Can you help me to learn more?
(Other definitions for warp that I've seen before include "Make or become out of shape" , "Make bent or twisted" , "Pervert - lengthways threads" , "Buckle" , "Distort as wood may from heat" .)