Architect agreed with son (6)
I believe the answer is:
rogers
'architect' is the definition.
(architect Richard Rogers)
'agreed with son' is the wordplay.
'agreed' becomes 'roger' (term meaning understood in radio communication).
'with' means one lot of letters go next to another.
'son' becomes 's'.
'roger'+'s'='ROGERS'
(Other definitions for rogers that I've seen before include "See 23" , "Amercian dancer and actress, Fred's partner" , "Ginger -, Fred Astaire partner" , "Ginger, maybe" , "See 7" .)