Two Florentine pieces once in circulation (6)
I believe the answer is:
florin
'two' is the definition.
The answer and definition can be both quantities as well as being singular nouns.
Maybe you can see an association between them that I don't see?
'florentine pieces once in circulation' is the wordplay.
I cannot quite see how this works, but
'in' is present in the answer.
The remaining letters 'flor' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for florin that I've seen before include "Former British silver coin" , "Pre-decimal coin" , "Old British (or Dutch) coin" , "ten pence" , "Old 2-shilling coin" .)