A bachelor has to bank on being just (6)
I believe the answer is:
barely
'just' is the definition.
('barely' can be a synonym of 'just')
'a bachelor has to bank on' is the wordplay.
'a bachelor' becomes 'ba' (the qualification: Bachelor of Arts).
'has' says to put letters next to each other.
'to bank on' becomes 'rely' (I've seen this before).
'ba'+'rely'='BARELY'
'being' is the link.
(Other definitions for barely that I've seen before include "Not quite" , "how streakers like to act?" , "how naturists exist" , "Just about, nothing to spare" , "By a small margin" .)