Dick Bach’s unusual bird (8)
I believe the answer is:
dabchick
'bird' is the definition.
(dabchick is a kind of bird)
'dick bach's unusual' is the wordplay.
'unusual' indicates anagramming the letters.
'dick'+'bach'='dickbach'
'dickbach' anagrammed gives 'DABCHICK'.
(Other definitions for dabchick that I've seen before include "Waterbird" , "Water bird - little grebe" , "good swimmer and diver" , "Small grebe" , "diving-bird" .)