Allowing the French time can start to grate (7)
I believe the answer is:
letting
'allowing' is the definition.
('let' can be a synonym of 'allow')
'the french time can start to grate' is the wordplay.
'the french' becomes 'le'.
'time' becomes 't'.
'can' becomes 'tin' ('tin' can be a synonym of 'can').
'start to' says to take the initial letters.
The initial letter of 'grate' is 'g'.
'le'+'t'+'tin'+'g'='LETTING'
(Other definitions for letting that I've seen before include "Renting out; allowing" , "Granting to a tenant" , "Giving permission to" , "property for temporary occupants?" , "Leasing (a property)" .)