Worm finally caught by a parting, wandering bird (9)
I believe the answer is:
ptarmigan
'bird' is the definition.
(ptarmigan is a kind of bird)
'worm finally caught by a parting wandering' is the wordplay.
'finally' indicates one should take the final letters.
'caught by' is an insertion indicator.
'wandering' indicates an anagram.
The last letter of 'worm' is 'm'.
'a'+'parting'='aparting'
'aparting' with letters rearranged gives 'ptarigan'.
'm' put into 'ptarigan' is 'PTARMIGAN'.
(Other definitions for ptarmigan that I've seen before include "Northern game bird - map rating (anag)" , "turns white in winter" , "Game bird, white in winter" , "Type of mountain grouse" , "Game bird living the high life" .)