Twist shellfish, pulling upwards while removing tail (4)
I believe the answer is:
warp
'twist' is the definition.
(I've seen this in another clue)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for warp that I've seen before include "Make or become out of shape" , "Become bent like timber through heat" , "Misintepret" , "Of wood, twist under heat" , "Pervert - lengthways threads" .)