Suggest Monsieur is welcomed into international fold (5)
I believe the answer is:
imply
'suggest' is the definition.
(implying is a kind of suggesting)
'monsieur is welcomed into international fold' is the wordplay.
'monsieur' becomes 'm' (French abbreviation - like Mr for Mister).
'is welcomed into' indicates putting letters inside.
'international' becomes 'i' (abbreviation eg in IMF).
'fold' becomes 'ply' (I've seen this before).
'i'+'ply'='iply'
'm' placed inside 'iply' is 'IMPLY'.
(Other definitions for imply that I've seen before include "Insinuate, hint" , "Mean" , "Express indirectly" , "State indirectly" , "Involve - intimate" .)