Covert remark by actor regarding hit song on record (5)
I believe the answer is:
aside
'covert remark' is the definition.
'aside' can be an answer for 'remark' (I have seen 'Confidential remark' mean 'aside' so perhaps 'remark' could also mean 'aside'). I am not certain of the 'covert' bit.
'by actor regarding hit song on record' is the wordplay.
I cannot quite see how this works, but
'by' could be 'side' (synonyms) and 'side' is found within the answer.
A single letter 'a' remains which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for aside that I've seen before include "Actors comment to his audience" , "Stage whisper" , "Apart; incidental remark" , "Remark by an actor, directly to audience say" , "(Turn) off main path" .)