Spot a woman’s plucked instrument (6)
I believe the answer is:
zither
'plucked instrument' is the definition.
'spot a woman's' is the wordplay.
'spot' becomes 'zit'.
'a woman' becomes 'her'.
'zit'+'her'='ZITHER'
(Other definitions for zither that I've seen before include "Harp-like instrument" , "Instrument played on the knee" , "music player" , "Metal-stringed soundbox" , "Stringed instrument placed on the knee" .)