Avoid making a decision (3,2,3,5)
I believe the answer is:
sit on the fence
'avoid making a decision' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for sit on the fence that I've seen before include "Don't commit oneself" , "Remain undecided" , "don't choose either?" , "refuse to support either side" , "Refuse to commit oneself" .)