Clever move possible to get voucher? (6)
I believe the answer is:
coupon
'voucher?' is the definition.
(I know that voucher can be written as coupon)
'clever move possible' is the wordplay.
'clever move' becomes 'coup' (I've seen this in another clue).
'possible' becomes 'on' ('not on' can mean unacceptable or not possible).
'coup'+'on'='COUPON'
'to get' is the link.
(Other definitions for coupon that I've seen before include "Voucher or ticket" , "means to buy goods" , "betting slip" , "Entry form" , "Token" .)