Here trade union breaking up conflict (7)
I believe the answer is:
auction
'here trade' is the definition.
(event where trade takes place)
'union breaking up conflict' is the wordplay.
'union' becomes 'u' (common abbreviation as in 'Trades Union Congress').
'breaking up' indicates putting letters inside (inserted letters slice into or 'break up' the word).
'conflict' becomes 'action' (as in military action).
'u' placed into 'action' is 'AUCTION'.
(Other definitions for auction that I've seen before include "Lots are sold here!" , "Public sale by bid" , "Public sale - type of bridge" , "Public sale at which bids are made" , "Competitive sale" .)