Dogs take a large bird into barbarous extremes (7)
I believe the answer is:
beagles
'dogs' is the definition.
(beagle is a kind of dog)
'a large bird into barbarous extremes' is the wordplay.
'a large bird' becomes 'eagle' (eagles are large birds).
'into' means one lot of letters goes inside another.
'extremes' suggests removing the centre.
'barbarous' with its middle removed is 'bs'.
'eagle' placed within 'bs' is 'BEAGLES'.
'take' is the link.
(Other definitions for beagles that I've seen before include "Short-legged hounds" , "Hunting hounds" , "These hounds bag eels badly" , "Dogs" .)