It's no good interrupting an SOS for musical entertainment (5)
I believe the answer is:
songs
'entertainment' is the definition.
(I know that songs is a type of music)
'it's no good interrupting an sos' is the wordplay.
'it's no good' becomes 'ng' (abbreviation).
'interrupting' means one lot of letters goes inside another.
'ng' inserted within 'sos' is 'SONGS'.
'for musical' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for songs that I've seen before include "Vocal compositions" , "Words with music" , "Airs" , "Anthems" , "Arias" .)