Smart young person, promising Scottish author (6,5)
I believe the answer is:
bright spark
'smart young person' is the definition.
(a bright young person)
'promising scottish author' is the wordplay.
'promising' becomes 'bright' (I've seen this before).
'scottish author' becomes 'Spark' (novelist Muriel Spark).
'bright'+'spark'='BRIGHT SPARK'
(Other definitions for bright spark that I've seen before include "one who has many good ideas" , "Clever person" , "Lively and clever individual" , "One full of ideas" , "Someone who appears (irritatingly?) clever" .)