Revenue from wager, not small (4)
I believe the answer is:
take
'revenue' is the definition.
(I've seen this in another clue)
'wager not small' is the wordplay.
'wager' becomes 'stake' (wager in poker).
'not' suggests deleting specific letters.
'small' becomes 's' (abbreviation - e.g. clothes size).
'stake' with 's' removed is 'TAKE'.
'from' is the link.
(Other definitions for take that I've seen before include "Money received" , "Accept or steal?" , "Remove, subtract" , "Consume (drugs)" , "scene filmed without interruption" .)