Live on edge (6)
I believe the answer is:
reside
'live' is the definition.
(residing is a kind of living)
'on edge' is the wordplay.
'on' becomes 're' ('on' can be mean 'with reference to').
'edge' becomes 'side' (edge can mean the side of something).
're'+'side'='RESIDE'
(Other definitions for reside that I've seen before include "Occupy a place" , "Live in permanently" , "Dwell, be present (in)" , "Lodge" , "Live (at an address)" .)