Creature said to do a bit of squirming (4)
I believe the answer is:
worm
'creature' is the definition.
(worm is a kind of creature)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for worm that I've seen before include "Squirm" , "Slither" , "Reproductive computer virus" , "Screw thread; maggot" , "Annelid" .)