Fight through trade winds (8,5)
I believe the answer is:
exchange blows
'fight' is the definition.
(exchanging blows is a kind of fighting)
'trade winds' is the wordplay.
'trade' becomes 'exchange' (exchange of items).
'winds' becomes 'blows' (blow is a kind of wind).
'exchange'+'blows'='EXCHANGE BLOWS'
'through' acts as a link.
(Other definitions for exchange blows that I've seen before include "Quarrel physically" , "Fight - angel chews box (anag)" , "Do battle with" .)