Unfriendly crowd on French island (7)
I believe the answer is:
hostile
'unfriendly' is the definition.
('hostile' can be similar in meaning to 'unfriendly')
'crowd on french island' is the wordplay.
'crowd' becomes 'host' (I've seen this before).
'on' means one lot of letters go next to another.
'french island' becomes 'ile' (French for 'island').
'host'+'ile'='HOSTILE'
(Other definitions for hostile that I've seen before include "Bellicose" , "Unkind" , "malevolent" , "Inimical" , "Antagonistic" .)