Dealing with jazz in Gateshead (7)
I believe the answer is:
trading
'dealing' is the definition.
(I know that trading is a type of commerce)
'with jazz in gateshead' is the wordplay.
'with' is a charade indicator (letters next to each other).
'jazz' becomes 'trad' (trad jazz is a type of jazz).
'gateshead' becomes 'g' (head letter of 'gates').
'trad' next to 'in' is 'tradin'.
'tradin'+'g'='TRADING'
(Other definitions for trading that I've seen before include "In business" , "Commercial activity" , "in the marketplace" , "Buying and selling" , "Dealing" .)