Board is to make progress (3,2)
I believe the answer is:
get on
This clue is a triple definition!
'board' is the first definition.
(synonyms)
'is to make' is the second definition.
(thesaurus)
'progress' is the third definition.
(synonyms)
(Other definitions for get on that I've seen before include "Make progress; be friends" , "What boarders do" , "Enjoy harmonious relationship" , "Make progress or climb aboard" , "Age; prosper" .)