Birds, initially ensnarled in gales, destroyed (6)
I believe the answer is:
eagles
'birds' is the definition.
(eagle is a kind of bird)
'initially ensnarled in gales destroyed' is the wordplay.
'initially' says to take the initial letters.
'in' means one lot of letters goes inside another.
'destroyed' indicates anagramming the letters.
The initial letter of 'ensnarled' is 'e'.
'gales' is an anagram of 'eagls'.
'e' going within 'eagls' is 'EAGLES'.
(Other definitions for eagles that I've seen before include "Keen-eyed birds" , "such hunters aren't often seen on course" , "Golf scores of two under par" , "Birds with a sea leg?" , "band" .)