Mug goes after old record by this fabulous group manager (7)
I believe the answer is:
epstein
'this fabulous group manager' is the definition.
The definition suggests a singular noun which matches the answer.
'mug goes after old record' is the wordplay.
'mug' becomes 'stein' (stein is a kind of mug).
'goes after' is a charade indicator (letters next to each other).
'old record' becomes 'EP' (abbreviation for extended play record).
'stein' put after 'ep' is 'EPSTEIN'.
'by' is the link.
Can you help me to learn more?
(Other definitions for epstein that I've seen before include "pop group's manager" , "Sir Jacob --, US-born British sculptor" , "Sir Jacob ..., sculptor noted for his statues of the famous" , "Brian --, Beatles manager" , "British sculptor, d. 1959 - Beatles manager, d. 1967" .)