Fish finger initially cut (3)
I believe the answer is:
eel
'fish' is the definition.
(I know that eel is a type of fish)
'finger initially cut' is the wordplay.
'finger' becomes 'feel' (synonyms).
'initially cut' means to remove the first letter (the initial is cut).
'feel' with its first letter removed is 'EEL'.
(Other definitions for eel that I've seen before include "Slippery type" , "Slender fish" , "Serpentine fish" , "Slippery swimmer (may be jellied)" , "Slippery person" .)