Bang on the coop (5)
I believe the answer is:
pound
This clue is a double definition.
'bang' is the first definition.
(thesaurus)
'the coop' is the second definition.
(thesaurus)
'on' is the link.
(Other definitions for pound that I've seen before include "Quid" , "# and lb" , "Cars towed to it; hit heavily" , "Hit repeatedly and hard" , "Powder - 16 oz - 100p" .)