Graduates of London University in the main, perhaps? (6)
I believe the answer is:
alumni
'graduates' is the definition.
('alumnus' can be a synonym of 'graduate')
'london university in the main perhaps?' is the wordplay.
'london university' becomes 'lu' (this might be a standard abbreviation which I don't know about).
'in the' indicates putting letters inside.
'perhaps?' is an anagram indicator (I've seen 'perhaps' mean this).
'main' anagrammed gives 'amni'.
'lu' put into 'amni' is 'ALUMNI'.
'of' is the link.
Can you help me to learn more?
(Other definitions for alumni that I've seen before include "Past pupils, Latin plural" , "we studied at a certain place" , "Past pupils or graduates" , "Former (school) pupils" , "Graduates of a college" .)