American leaves home for university party (4)
I believe the answer is:
camp
'party' is the definition.
(both can mean a group of people)
'american leaves home for university' is the wordplay.
I cannot really understand how this works, but
'american' could be 'am' (abbreviation in some contexts) and 'am' is found within the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for camp that I've seen before include "military depot" , "Where guys are tense" , "Effeminate; military base" , "Military settlement" , "Hill fort; extravagantly theatrical" .)