Settle with a right instrument (5)
I believe the answer is:
sitar
'instrument' is the definition.
(sitar is a kind of instrument)
'settle with a right' is the wordplay.
'settle with' becomes 'sit' (I can't justify this - if you can you should give a lot more credence to this answer).
'a right' becomes 'ar' (I've seen this in other clues).
'sit'+'ar'='SITAR'
Can you help me to learn more?
(Other definitions for sitar that I've seen before include "Astir with Indian long-necked lute" , "Long necked and often plucked" , "Long-necked musical instrument of India" , "Guitar-like instrument" , "Plucked instrument" .)