Working version of credit (2,7)
I believe the answer is:
on account
'credit' is the definition.
'working version' is the wordplay.
'working' becomes 'on'.
'version' becomes 'account'.
'on'+'account'='ON ACCOUNT'
'of' acts as a link.
(Other definitions for on account that I've seen before include "an instalment" , "By deferred payment" , "As partial payment with the rest to come later" , "To be paid" , "Involving part payment" .)