Artist profits, having place for market in London (12)
I believe the answer is:
gainsborough
'artist' is the definition.
(Gainsborough is an example)
'profits having place for market in london' is the wordplay.
I cannot quite see how this works, but
'profits' could be 'gains' ('gain' can be a synonym of 'profit') and 'gains' is present in the answer.
'place' could be 'rough' (rough is a kind of place) and 'rough' is located in the answer.
The remaining letters 'bo' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for gainsborough that I've seen before include "Arty type" , "Lincolnshire town -- 18th-century English painter" , "Canvasser" , "See 14" , "Thomas -, eighteen century English painter" .)