Let it stand, accept record by a musical group (6)
I believe the answer is:
septet
'a musical group' is the definition.
(septet is a kind of musical group)
'let it stand accept record' is the wordplay.
'let it stand' becomes 'stet' (I've seen this before).
'accept' is an insertion indicator.
'record' becomes 'ep' (abbreviation for extended play record).
'stet' enclosing 'ep' is 'SEPTET'.
'by' acts as a link.
(Other definitions for septet that I've seen before include "Musical group" , "Odd number of players performing" , "Heptad" , "Band of seven players" , "Work for seven players" .)