Old French currency is for animal-loving saint (7)
I believe the answer is:
francis
'saint' is the definition.
(Pope Francis)
'old french currency is' is the wordplay.
'old french currency' becomes 'franc' (I've seen this before).
'franc'+'is'='FRANCIS'
'for animal-loving' is the link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for francis that I've seen before include "Man" , "My Lady Poverty saint" , "Pope" , "English philosopher, d. 1626 -- Dublin-born painter, d. 1992" , "Patron saint of animals" .)