Here, trade union stops conflict (7)
I believe the answer is:
auction
'here trade' is the definition.
(event where trade takes place)
'union stops conflict' is the wordplay.
'union' becomes 'U' (common abbreviation as in Trades Union Congress).
'stops' indicates putting letters inside (stopping can mean blocking a gap).
'conflict' becomes 'action' (as in military action).
'u' put into 'action' is 'AUCTION'.
(Other definitions for auction that I've seen before include "Competitive sale" , "Public sale with lots" , "A lot will be seen in this" , "Offer to bidders" , "Public sale - type of bridge" .)