Beatles manager Brian records 'One In Ten' (7)
I believe the answer is:
epstein
'beatles manager brian' is the definition.
(I've seen this in another clue)
'records one in ten' is the wordplay.
'records' becomes 'EPs' (EP is a type of record).
'one' becomes 'i' (Roman numeral).
'in' means one lot of letters goes inside another.
'i' inserted within 'ten' is 'tein'.
'eps'+'tein'='EPSTEIN'
(Other definitions for epstein that I've seen before include "American-born British sculptor, d. 1959" , "Sir Jacob --, US-born British sculptor" , "produced a few bronzes" , "British sculptor, d. 1959 - Beatles manager, d. 1967" , "Brian --, Beatles manager" .)