Money on commission for experimental rig (10)
I believe the answer is:
breadboard
'experimental rig' is the definition.
(electronics term)
'money on commission' is the wordplay.
'money' becomes 'bread' (bread is slang for money).
'on' means one lot of letters go next to another (in a down clue, letters appear on others).
'commission' becomes 'board' (board is a kind of commission).
'bread'+'board'='BREADBOARD'
'for' is the link.
(Other definitions for breadboard that I've seen before include "doorsteps produced" , "cutting bloomers here?" , "it's where cuts will be made" , "Base for cutting loaf" , "Where circuits may be tried out" .)