Middle of crustacean possibly uncooked? (3)
I believe the answer is:
raw
'uncooked?' is the definition.
('raw' can be similar in meaning to 'uncooked')
'middle of crustacean' is the wordplay.
'middle of' indicates the central letters.
'crustacean' becomes 'prawn' (prawn is a kind of crustacean).
The central letters of 'prawn' are 'RAW'.
'possibly' is the link.
(Other definitions for raw that I've seen before include "Inexperienced in war (3)" , "Damp and chilly" , "Like a recruit" , "Untried (of recruit) - uncooked (of meat)" , "Natural" .)