Worker with quarter stake (4)
I believe the answer is:
ante
'stake' is the definition.
(I've seen this before)
'worker with quarter' is the wordplay.
'worker' becomes 'ant' (worker is a type of ant**).
'with' means one lot of letters go next to another.
'quarter' becomes 'e'.
'ant'+'e'='ANTE'
(Other definitions for ante that I've seen before include "Stake (that may be upped?)" , "Betting stake" , "Money put at risk" , "A neat sort of prefix" , "Stake put up by a poker-player before receiving cards" .)