Feel in form like a cat (6)
I believe the answer is:
feline
'like a cat' is the definition.
(I've seen this before)
'feel in form' is the wordplay.
'form' indicates an anagram (another form of the letters).
'feel'+'in'='feelin'
'feelin' is an anagram of 'FELINE'.
(Other definitions for feline that I've seen before include "Pertaining to cats" , "suitable for Skimbleshanks?" , "An animal of the cat family" , "16 [TOM] perhaps" , "Scots dish" .)