Old American round piano gets musical work (4)
I believe the answer is:
opus
'musical work' is the definition.
(I've seen this before)
'old american round piano' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'american' becomes 'us'.
'round' indicates putting letters inside.
'piano' becomes 'p'.
'o'+'us'='ous'
'ous' placed around 'p' is 'OPUS'.
'gets' acts as a link.
(Other definitions for opus that I've seen before include "Composer's work" , "Artistic work" , "Work (mus.)" , "Musical piece" , "Showing creative skill" .)