Gifted boy in marquee with editor (8)
I believe the answer is:
talented
'gifted' is the definition.
(I know that gifted can be written as talented)
'boy in marquee with editor' is the wordplay.
'boy' becomes 'Al'.
'in' means one lot of letters goes inside another.
'marquee' becomes 'tent' (marquee is a type of tent).
'with' says to put letters next to each other.
'editor' becomes 'ed' (abbreviation).
'al' inserted into 'tent' is 'talent'.
'talent'+'ed'='TALENTED'
(Other definitions for talented that I've seen before include "Possessing ability" , "Well-endowed with gifts" , "Skilled" , "Having a natural aptitude or skill" , "Naturally gifted" .)