Music at the heart of proper stereo beats (5)
I believe the answer is:
opera
'music' is the definition.
(opera is a kind of music)
'at the heart of proper stereo beats' is the wordplay.
'at' means one lot of letters go next to another.
'the heart of' says to take the centre.
'stereo beats' becomes 'era' (I can't explain this - if you can you should believe this answer much more).
The central letters of 'proper' are 'op'.
'op' put next to 'era' is 'OPERA'.
Can you help me to learn more?
(Other definitions for opera that I've seen before include "La Boheme or Rigoletto" , "Falstaff, say" , "Macbeth for one" , "E.g. Macbeth, Falstaff" , "could be soap" .)