Relative newcomer's first record cut (6)
I believe the answer is:
nephew
'relative' is the definition.
(type of relative)
'newcomer's first record cut' is the wordplay.
'newcomer's first' becomes 'n' (1st letter of 'newcomer').
'record' becomes 'EP' (abbreviation for extended play record).
'cut' becomes 'hew' (hew can mean to chop or cut).
'n'+'ep'+'hew'='NEPHEW'
(Other definitions for nephew that I've seen before include "Sister's son" , "Has a duty (to do something)" , "Kinsman" , "Family relative" , "A sibling's child" .)