Respecting boy fencing area in grounds (6)
I believe the answer is:
reason
'grounds' is the definition.
(I've seen this before)
'respecting boy fencing area' is the wordplay.
'respecting' becomes 're' (regarding).
'boy' becomes 'son' (synonyms).
'fencing' indicates putting letters inside (to fence can mean to contain or put a limit round).
'area' becomes 'a' (maths abbreviation).
're'+'son'='reson'
'reson' enclosing 'a' is 'REASON'.
'in' acts as a link.
(Other definitions for reason that I've seen before include "Deduce" , "brain operations" , "Sanity of senora" , "Logic of senora" , "Sanity and logic" .)