Again a child has justification (6)
I believe the answer is:
reason
'justification' is the definition.
(I know that reason is a type of justification)
'again a child' is the wordplay.
'again' becomes 're' (prefix meaning 'again').
'child' becomes 'son' (male child).
're'+'a'+'son'='REASON'
'has' is the link.
(Other definitions for reason that I've seen before include "Logic; excuse" , "Mental power to justify an act" , "Power of thought" , "Cause; think logically" , "Sanity, the ability to think" .)