Gym in French street makes money (5)
I believe the answer is:
rupee
'money' is the definition.
(currency of India)
'gym in french street' is the wordplay.
'gym' becomes 'pe' (short for Physical Education).
'in' is an insertion indicator.
'french street' becomes 'rue' (French for street or road).
'pe' put inside 'rue' is 'RUPEE'.
'makes' is the link.
(Other definitions for rupee that I've seen before include "low cost in Pakistan?" , "Indian coin" , "Unit of money in India" , "foreign currency" , "Indian rhino" .)