A strip under bottom of small washer (9)
I believe the answer is:
laundress
'washer' is the definition.
(laundress is a kind of washer)
'a strip under bottom of small' is the wordplay.
'strip' becomes 'undress' ('undress' can be a synonym of 'strip'**).
'under' means one lot of letters go next to another.
'bottom of' says to take the final letters.
The last letter of 'small' is 'l'.
'a'+'undress'='aundress'
'aundress' after 'l' is 'LAUNDRESS'.
(Other definitions for laundress that I've seen before include "She'll clean" , "Disguise for jailbreaker in famous tale" , "Woman who washes clothes for a living" , "Washerwoman" , "Woman washing clothes" .)