Remain uncommitted, being held up by barrier? (3,2,3,5)
I believe the answer is:
sit on the fence
I believe this clue is a double definition.
'remain uncommitted' is the first definition.
(to sit on the fence is to refuse to take sides)
'being held up by barrier?' is the second definition.
(literally sitting on a fence)
(Other definitions for sit on the fence that I've seen before include "Avoid committing oneself; be neutral" , "Survey two gardens" , "Avoid making a decision" , "don't choose either?" , "Refuse to commit oneself" .)