An instrumental piece shows how to play this (5)
I believe the answer is:
banjo
This could be a double definition.
'an instrumental piece' is the first definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe you can see a link between them that I can't see?
'how to play this' is the second definition.
The definition suggests a singular noun which matches the answer.
'shows' acts as a link.
Can you help me to learn more?
(Other definitions for banjo that I've seen before include "Guitar-like instrument" , "Softly (music)" , "String instrument" , "Stringed instrument beloved of old minstrel shows" , "No jab (anag.)" .)