Possibly feeling no end catty (6)
I believe the answer is:
feline
'catty' is the definition.
(I've seen this in another clue)
'possibly feeling no end' is the wordplay.
'possibly' indicates anagramming the letters.
'no end' means to remove the last letter.
'feeling' with its last letter taken off is 'feelin'.
'feelin' anagrammed gives 'FELINE'.
(Other definitions for feline that I've seen before include "Like a cat" , "Cat-like" , "Relating to cats" , "(Relating to a) cat" , "Of or like cats" .)