Bird finally perching in a gnarled tree (5)
I believe the answer is:
egret
'bird' is the definition.
(egret is a kind of bird)
'finally perching in a gnarled tree' is the wordplay.
'finally' says to take the final letters.
'in' is an insertion indicator.
'a gnarled' indicates anagramming the letters (I've seen this in other clues).
The final letter of 'perching' is 'g'.
'tree' with letters rearranged gives 'eret'.
'g' going into 'eret' is 'EGRET'.
(Other definitions for egret that I've seen before include "(Usually) white heron" , "White-plumed wader" , "white fish eater" , "Mainly white heron" , "Wader with white plumage" .)