It reproduces music from short film about Returning Officers' credentials (7,4,6)
I believe the answer is:
compact disc player
'returning officers' credentials' is the definition.
I don't know anything about this answer so I cannot tell whether this works.
'it reproduces music from short film about' is the wordplay.
I cannot really see how this works, but
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is located in the answer.
'music' could be 'lay' (lay is a kind of music) and 'lay' is found in the answer.
'from' could be 'o' (I've seen this in other clues) and 'o' is found in the answer.
'film' could be 'm' (1931 Fritz Lang film) and 'm' is present in the answer.
'about' could be 'c' (abbreviation for 'circa') and 'c' is found within the answer.
This explanation may well be incorrect...
Can you help me to learn more?