Good college board (5)
'board' is the definition.
(I've seen this before)
'good college' is the wordplay.
'good' becomes 'g' (abbreviation).
'college' becomes 'eton' (I've seen this before).
'g'+'eton'='GET ON'
(Other definitions for get on that I've seen before include "Make progress or climb aboard" , "Advance; prosper" , "What boarders do" , "Hit it off" , "Make progress or advance in age" .)