Possibly feeling no end catty (6)
I believe the answer is:
feline
'catty' is the definition.
(thesaurus)
'possibly feeling no end' is the wordplay.
'possibly' indicates anagramming the letters.
'no end' means to remove the last letter.
'feeling' with its final letter removed is 'feelin'.
'feelin' with letters rearranged 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" .)