Token Rev returns with sound of pain (7)
I believe the answer is:
voucher
'token' is the definition.
(both can mean a ticket carrying a discount)
'rev returns with sound of pain' is the wordplay.
'returns' says the letters should be written backwards.
'with' indicates putting letters inside.
'sound of pain' becomes 'ouch' (I've seen this in another clue).
'rev' written backwards gives 'ver'.
'ver' placed around 'ouch' is 'VOUCHER'.
(Other definitions for voucher that I've seen before include "Something that can be exchanged for goods or services" , "Coupon; receipt" , "Ticket" , "Document that can be exchanged for goods" , "Document that serves as evidence of some expenditure" .)