Maybe a glen provides cover for such a bird (5)
I believe the answer is:
eagle
'such a bird' is the definition.
(eagle is a type of bird)
'maybe a glen provides cover' is the wordplay.
'cover' indicates the answer is hidden within the clue (I've seen 'covered' mean this (the answer is covered up by the clue)).
'EAGLE' is hidden within 'maybe a glen provides'.
'for' acts as a link.
(Other definitions for eagle that I've seen before include "Flyer" , "might one be bald?" , "standard for the military is seen" , "flier" , "Old comic" .)