Smell bad in the Home Counties? Then wash! (6)
I believe the answer is:
sponge
'wash' is the definition.
(thesaurus)
'smell bad in the home counties?' is the wordplay.
'smell bad' becomes 'pong' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'in' means one lot of letters goes inside another.
'the home counties?' becomes 'se' (Home Counties in the South East of England).
'pong' going into 'se' is 'SPONGE'.
'then' acts as a link.
Can you help me to learn more?
(Other definitions for sponge that I've seen before include "Porous fibres for soaking up" , "Aquatic creature; cake" , "clean with damp cloth" , "Cadge - porous object used for washing" , "Absorbent cleaner - cadge" .)