A store of French cannabis (5)
I believe the answer is:
depot
'a store' is the definition.
(depot can mean a store or warehouse)
'of french cannabis' is the wordplay.
'of french' becomes 'de' ('of' in French).
'cannabis' becomes 'pot' (synonyms).
'de'+'pot'='DEPOT'
(Other definitions for depot that I've seen before include "(Military) store" , "Toped (anag.)" , "Regimental HQ" , "Place for storing or despatching goods" , "Terminus for transport vehicles" .)