Provide support for a foreigner reported to be drunk (12)
I believe the answer is:
bacchanalian
'be drunk' is the definition.
(thesaurus)
'provide support for a foreigner reported' is the wordplay.
'provide support for' becomes 'bacch' (I can't explain this - if you can you should give a lot more credence to this answer).
'a' becomes 'an'.
'foreigner' becomes 'alien' (synonyms).
'reported' indicates a 'sounds like' (homophone) clue.
'alien' sounds like 'alian'.
'bacch'+'an'+'alian'='BACCHANALIAN'
'to' is the link.
(Other definitions for bacchanalian that I've seen before include "description of drunken revels" , "Relating to drunken revelry" , "Drunken, orgiastic (revel)" , "drunken reveller" .)