Advice from “mother” for one wife and female (3,4)
I believe the answer is:
say when
'advice from mother' is the definition.
('mother' is the person pouring out tea)
'for one wife and female' is the wordplay.
'for one' becomes 'say' (both can mean 'for example').
'wife' becomes 'w'.
'and' means one lot of letters go next to another.
'female' becomes 'hen' (hen is a kind of female).
'say'+'w'+'hen'='SAY WHEN'
(Other definitions for say when that I've seen before include "Request to be told to stop pouring drink" , "Words from the pourer?" , "Tell me when to stop pouring" , "Pourer's words" .)