Live with Satan Bug (7)
I believe the answer is:
bedevil
'bug' is the definition.
(I've seen this before)
'live with satan' is the wordplay.
'live' becomes 'be' (synonyms).
'with' says to put letters next to each other.
'satan' becomes 'Devil' (synonyms).
'be'+'devil'='BEDEVIL'
(Other definitions for bedevil that I've seen before include "Vile bed (anag.)" , "Cause continual difficulties" , "Cause difficulties for, like Satan?" , "Torture" , "Bug" .)