Hire out first-born son, perhaps (4)
I believe the answer is:
heir
'first-born son perhaps' is the definition.
I can't judge whether this defines the answer.
'hire out' is the wordplay.
'out' is an anagram indicator (out can mean wrong or inaccurate).
'hire' anagrammed gives 'HEIR'.
Can you help me to learn more?
(Other definitions for heir that I've seen before include "One destined to succeed" , "One who succeeds" , "One likely to succeed" , "Acknowledged beneficiary" , "Beneficiary, inheritor" .)