Strip on big US city is cleaner (9)
I believe the answer is:
laundress
'is cleaner' is the definition.
(I've seen this before)
'strip on big us city' is the wordplay.
'strip' becomes 'undress' (synonyms).
'on' says to put letters next to each other.
'big us city' becomes 'la' (I can't explain this - if you can you should believe this answer much more).
'undress' after 'la' is 'LAUNDRESS'.
Can you help me to learn more?
(Other definitions for laundress that I've seen before include "Disguise for jailbreaker in famous tale" , "Woman who washes clothes for a living" , "who's got her clothes?" , "Washerwoman" , "Woman washing clothes" .)