Bird to wail about wrong tag (7)
I believe the answer is:
wagtail
'bird' is the definition.
(wagtail is a kind of bird)
'wail about wrong tag' is the wordplay.
'about' is an insertion indicator.
'wrong' indicates an anagram.
'tag' is an anagram of 'agt'.
'wail' placed around 'agt' is 'WAGTAIL'.
'to' acts as a link.
(Other definitions for wagtail that I've seen before include "'Bird, its posterior projection jerks up and down (7)'" , "Small bird (pied/yellow)" , "Slender songbird - a law git (anag)" , "singer" , "I tag law of the bird" .)