Time to relax on the French island? Certainly! (7)
I believe the answer is:
leisure
'time to relax' is the definition.
(I've seen this in another clue)
'on the french island? certainly' is the wordplay.
'on' says to put letters next to each other.
'the french' becomes 'le' ('the' in French).
'island?' becomes 'i' (geographical abbreviation).
'certainly' becomes 'sure' (synonyms).
'le'+'i' is 'lei'.
'lei'+'sure'='LEISURE'
(Other definitions for leisure that I've seen before include "Time for relaxing" , "Time away from work" , "Use lire (anag)" , "Ease; time off work" , "Breathing space" .)