Self-help group covering roughly half the folk on campus (8)
I believe the answer is:
academia
'the folk on campus' is the definition.
(people on a university campus)
'self-help group covering roughly half' is the wordplay.
'self-help group' becomes 'aa' (Alcoholics Anonymous).
'covering' means one lot of letters goes inside another.
'roughly' becomes 'ca'.
'half' becomes 'demi' (prefix as in 'demigod').
'ca'+'demi'='cademi'
'aa' going around 'cademi' is 'ACADEMIA'.
(Other definitions for academia that I've seen before include "educational environment" , "The world of teaching" , "World of university and learning" , "university life" , "Teaching environment" .)