Pay for indulgence (5)
I believe the answer is:
treat
This clue is a double definition.
'pay for' is the first definition.
(I've seen this before)
'indulgence' is the second definition.
(to indulge yourself is to treat yourself)
(Other definitions for treat that I've seen before include "Negotiate to reach an agreement" , "Apply remedies" , "Event causing special pleasure" , "Alternative to trick" , "Pay for someone else's enjoyment" .)