Debate about a boy (6)
I believe the answer is:
reason
'debate' is the definition.
(reason can mean to consider or debate)
'about a boy' is the wordplay.
'about' becomes 'rea' (I've seen this in other clues).
'a boy' becomes 'son' (synonyms).
'rea'+'son'='REASON'
(Other definitions for reason that I've seen before include "The right exercise of the mind" , "issue" , "Cause to perform" , "Sanity and logic" , "Cause or motive" .)