Perform a vocal duet in an American prison? (4,4)
I believe the answer is:
'an american prison?' is the definition.
'Sing Sing' can be an answer for 'prison?' (US prison). I am not certain of the 'an american' bit.
'perform a vocal duet' is the wordplay.
'perform' becomes 'sing'.
'a vocal duet' becomes 'sing' (I can't justify this - if you can you should give a lot more credence to this answer).
'in' acts as a link.
Can you help me to learn more?
(Other definitions for sing sing that I've seen before include "NY prison" , "New York state prison" .)