Slippery sort, somewhat unfeeling (3)
I believe the answer is:
eel
'slippery sort' is the definition.
(I've seen this in another clue)
'somewhat unfeeling' is the wordplay.
'somewhat' indicates a hidden word.
'EEL' is hidden in the letters of 'unfeeling'.
(Other definitions for eel that I've seen before include "Snakelike fish" , "Fish in the Lee?" , "Slippery person" , "Elongated fish" , "A sea snake" .)