Bargain brooches sent to the north (4)
I believe the answer is:
snip
'bargain' is the definition.
(slang term for a good deal)
'brooches sent to the north' is the wordplay.
'brooches' becomes 'pins'.
'sent to the north' is a reversal indicator (in a down clue, letters go up).
'pins' reversed gives 'SNIP'.
(Other definitions for snip that I've seen before include "Bargain (coll)" , "Cut using pins" , "Cut with scissors in small strokes" , "Cut - price bargain" , "Surprisingly cheap item" .)