Support mother during visit? (8)
I believe the answer is:
mainstay
'support' is the definition.
(I know that mainstay is a type of support)
'mother during visit?' is the wordplay.
'mother' becomes 'ma' (ma can mean mother).
'during' becomes 'in' (e.g. during February means in February).
'visit?' becomes 'stay' (visit is a kind of stay).
'ma'+'in'+'stay'='MAINSTAY'
(Other definitions for mainstay that I've seen before include "Strongest support" , "chief supporter" , "Strong cable that secures a mast, chief support generally" , "Linchpin, principal support" , "Linchpin, principle support" .)