Be at school with the Mrs (6)
I believe the answer is:
beeton
'the mrs' is the definition.
I don't know anything about this answer so I can't judge whether this works.
'be at school' is the wordplay.
'at' means one lot of letters go next to another.
'school' becomes 'eton' (famous UK public school).
'be'+'eton'='BEETON'
'with' is the link.
Can you help me to learn more?
(Other definitions for beeton that I've seen before include "Old cook" , "Mrs -, cookery writer" , "She helped us to cook" , "Mrs --, cookbook writer" , "Woman" .)