In agreement, or working towards the same goal (6)
I believe the answer is:
onside
I believe this is a double definition.
'in agreement' is the first definition.
(I've seen this before)
'working towards the same goal' is the second definition.
(I've seen this before)
(Other definitions for onside that I've seen before include "Legally positioned at football etc" , "(In football) not in forbidden zone" , "Cricket's leg" , "Legally positioned in game" , "in position to proceed?" .)