Check about mother's stay (6)
I believe the answer is:
remain
'stay' is the definition.
(synonyms)
'check about mother's' is the wordplay.
'check' becomes 'rein' (both can mean to control or limit).
'about' means one lot of letters goes inside another.
'mother' becomes 'ma' (ma can mean mother).
'rein' placed around 'ma' is 'REMAIN'.
(Other definitions for remain that I've seen before include "Stay on after others have gone" , "stop behind?" , "Airmen (anag.)" , "Marine (anag)" , "Stay, don't go" .)