Destined to accept benefit, start to hire musical instrument (6,4)
I believe the answer is:
basset horn
'musical instrument' is the definition.
(basset horn is a kind of musical instrument)
'destined to accept benefit start to hire' is the wordplay.
'destined' becomes 'born' (I've seen this before).
'to accept' means one lot of letters goes inside another.
'benefit' becomes 'asset' (I've seen this before).
'start to' indicates taking the first letters.
The initial letter of 'hire' is 'h'.
'asset'+'h'='asseth'
'born' placed around 'asseth' is 'BASSET-HORN'.
(Another definition for basset horn that I've seen is " instrument".)