Managing to be top (6)
I believe the answer is:
coping
I believe this clue is a double definition.
'managing' is the first definition.
('cope' can be a synonym of 'manage')
'be top' is the second definition.
(I have seen 'top of wall' mean 'coping' so perhaps 'top' could also mean 'coping')
'to' is the link.
(Other definitions for coping that I've seen before include "Capping along the top of a stone wall" , "Managing - top course of a wall" , "Sloping top of a stone wall" , "Contending with - wall masonry" , "wall feature" .)