Join to get the club promoted (4,2)
I believe the answer is:
team up
'join' is the definition.
(I've seen this before)
'get the club promoted' is the wordplay.
'get' says to put letters next to each other.
'the club' becomes 'team' (as in a football club).
'promoted' becomes 'up' (moving up).
'team' next to 'up' is 'TEAM UP'.
'to' acts as a link.
(Other definitions for team up that I've seen before include "Unite for a common goal" , "Brighton and Hove Albion following promotion?" , "Couple" , "Join" .)