The point of About a Boy (6)
I believe the answer is:
reason
'the point' is the definition.
(thesaurus)
'about a boy' is the wordplay.
'about' becomes 'rea' (I've seen this in other clues).
'a boy' becomes 'son' ('son' can be a synonym of 'boy'**).
'rea'+'son'='REASON'
'of' is the link.
(Other definitions for reason that I've seen before include "Employ logic" , "Explanation or motive" , "Logic; excuse" , "Mental power to justify an act" , "Logic, sense" .)