Remain uncommitted (3,2,3,5)
I believe the answer is:
sit on the fence
'remain uncommitted' is the definition.
(to sit on the fence is to refuse to take sides)
This is the entire clue.
(Other definitions for sit on the fence that I've seen before include "Remain undecided" , "refuse to support either side" , "Refuse to decide" , "Avoid committing oneself; be neutral" , "Refuse to commit oneself" .)