Stay, and mother is in control (6)
I believe the answer is:
remain
'stay' is the definition.
('remain' can be a synonym of 'stay')
'mother is in control' is the wordplay.
'mother' becomes 'ma' (ma is a kind of mother).
'is in' means one lot of letters goes inside another.
'control' becomes 'rein' (rein is a kind of control).
'ma' going into 'rein' is 'REMAIN'.
'and' acts as a link.
(Other definitions for remain that I've seen before include "Old dance" , "Marine (anag)" , "Airmen (anag.)" , "Stay on after others have gone" , "Last" .)