Stone accepts sex trouble (7)
I believe the answer is:
agitate
'trouble' is the definition.
(agitating is a kind of troubling)
'stone accepts sex' is the wordplay.
'stone' becomes 'agate' (I've seen this before).
'accepts' indicates putting letters inside.
'sex' becomes 'it' (a common euphemism).
'agate' placed around 'it' is 'AGITATE'.
(Other definitions for agitate that I've seen before include "Get upset" , "rock" , "Upset, disturb the surface of" , "Stir violently" , "Incite" .)