American's phone ring — it may produce a tune (5)
I believe the answer is:
cello
'it may produce a tune' is the definition.
The definition suggests a singular noun which matches the answer.
'american's phone ring' is the wordplay.
'american's phone' becomes 'cell' (I can't justify this - if you can you should believe this answer much more).
'ring' becomes 'O' (letter resembling a ring).
'cell'+'o'='CELLO'
Can you help me to learn more?
(Other definitions for cello that I've seen before include "String quartet instrument" , "large-scale fiddle" , "Bass stringed instrument" , "Jacqueline du Pre's instrument" , "music produced by this?" .)