See apt conversion for former currency (6)
I believe the answer is:
peseta
'former currency' is the definition.
(I've seen this before)
'see apt conversion' is the wordplay.
'conversion' indicates anagramming the letters.
'see'+'apt'='seeapt'
'seeapt' is an anagram of 'PESETA'.
'for' is the link.
(Other definitions for peseta that I've seen before include "Spain's former currency unit" , "Spanish bread once" , "One hundred centimos" , "Spanish coinage" , "Old money - see Pat (anag)" .)