Instrument in two dimensions - cut and polish (9)
I believe the answer is:
xylophone
'instrument' is the definition.
(I know that xylophone is a type of percussion instrument)
'two dimensions cut and polish' is the wordplay.
I cannot quite see how this works, but
'cut' could be 'lop' (lopping is a kind of cutting) and 'lop' is located in the answer.
'and' could be 'n' (common abbreviation for 'and') and 'n' is found in the answer.
This explanation may well be incorrect...
'in' acts as a link.
Can you help me to learn more?
(Other definitions for xylophone that I've seen before include "Instrument with wooden bars to be struck" , "Percussion instrument played with small mallets" , "Patrick Moore's instrument" , "Percussion instrument played with mallet" , "Musical instrument with bars" .)