Title adopted by British author's a clever one (6,5)
I believe the answer is:
bright spark
'a clever one' is the definition.
(term for a clever person)
'title adopted by british author's' is the wordplay.
'title' becomes 'right' (I've seen this before).
'adopted by' is an insertion indicator (I've seen this in other clues).
'british' becomes 'b' (abbreviation e.g. in 'BBC').
'author' becomes 'spark' (author Muriel Spark).
'b'+'spark'='bspark'
'right' inserted into 'bspark' is 'BRIGHT SPARK'.
(Other definitions for bright spark that I've seen before include "ironically, one that's witty" , "one who has many good ideas" , "Clever person" , "One full of ideas" , "Someone who appears (irritatingly?) clever" .)