Make good on firm promises initially after university (6)
I believe the answer is:
recoup
'make good' is the definition.
('recoup' can be a synonym of 'make good')
'on firm promises initially after university' is the wordplay.
'on' becomes 're' ('on' can be mean 'with reference to'**).
'firm' becomes 'co' (a firm is a company).
'initially' indicates taking the first letters.
'after' is a charade indicator (letters next to each other).
'university' becomes 'u'.
The initial letter of 'promises' is 'p'.
'p' after 'u' is 'up'.
're'+'co'+'up'='RECOUP'
(Other definitions for recoup that I've seen before include "Regain (something lost)" , "make good one's losses" , "Recover - retrieve" , "Indemnify" , "Get back again, say losses (6)" .)