Tenant the French understand (6)
I believe the answer is:
lessee
'tenant' is the definition.
(I know that tenant can be written as lessee)
'the french understand' is the wordplay.
'the french' becomes 'les' (plural form of 'the' in French).
'understand' becomes 'see' (synonyms).
'les'+'see'='LESSEE'
(Other definitions for lessee that I've seen before include "Leaseholder" , "Tenant who holds a lease" , "Person who rents" , "Contractor" , "One renting a property" .)