Instrument that puts that woman on the spot (6)
I believe the answer is:
zither
'instrument' is the definition.
(I know that zither is a type of stringed instrument)
'that woman on the spot' is the wordplay.
'that woman' becomes 'her' ('her' refers to a woman).
'on' means one lot of letters go next to another.
'the spot' becomes 'zit' (spot on one's body).
'her' after 'zit' is 'ZITHER'.
'that puts' acts as a link.
(Other definitions for zither that I've seen before include "Stringed instrument placed on the knee" , "Harp-like instrument" , "Plucked musical instrument" , "Instrument played on the knees" , "Metal-stringed soundbox" .)