Not entirely practical, a marinated appetiser perhaps (8)
I believe the answer is:
calamari
'appetiser perhaps' is the definition.
I can't tell whether this defines the answer.
'not entirely practical a marinated' is the wordplay.
'not entirely' says the answer is hidden in the clue.
'CALAMARI' is hidden in the letters of 'practical a marinated'.
Can you help me to learn more?
(Other definitions for calamari that I've seen before include "Mediterranean cooked squid" , "Dish of squid" , "Squid served as food" , "Battered squid rings" , "seafood" .)