Look back in the Middle Ages for such birds (5)
I believe the answer is:
geese
'birds' is the definition.
(goose is a kind of bird)
'look back in the middle ages' is the wordplay.
'look' becomes 'see'.
'back' is a reversal indicator.
'in' is an insertion indicator.
'the middle' indicates the central letters (I've seen 'the middle of' mean this).
The middle letters of 'ages' are 'ge'.
'see' backwards is 'ees'.
'ees' put inside 'ge' is 'GEESE'.
'for such' acts as a link.
(Other definitions for geese that I've seen before include "Christmas birds" , "Birds in a gaggle" , "Domesticated fowl" , "Waterfowl" , "Aquatic birds - complete jackasses" .)