Standard urn, say, for prize (7)
I believe the answer is:
jackpot
'prize' is the definition.
(jackpot is a kind of prize)
'standard urn say' is the wordplay.
'standard' becomes 'jack' (both can refer to a flag).
'urn say' becomes 'pot' (urn is a kind of pot).
'jack'+'pot'='JACKPOT'
'for' is the link.
(Other definitions for jackpot that I've seen before include "First prize" , "pool" , "Hit the . . . . . . . - win the big prize" , "Large cash prize" , "Cumulative prize" .)