Voucher for purchase of no real value (5)
I believe the answer is:
token
I believe this is a double definition.
'voucher for purchase' is the first definition.
'of no real value' is the second definition.
(as in a token gesture)
(Other definitions for token that I've seen before include "Symbol; metal disc" , "Perfunctory" , "Something of sentimental value" , "Nominal; voucher" , "Done only as a symbolic gesture" .)