Unaffected by a turn performed by a novice (7)
I believe the answer is:
natural
'unaffected' is the definition.
(synonyms)
'a turn performed by a novice' is the wordplay.
'performed' is an anagram indicator.
'by' says to put letters next to each other.
'novice' becomes 'l' (as in a learner driver with L-plates on their car).
'a'+'turn'='aturn'
'aturn' with letters rearranged gives 'natur'.
'natur'+'a'+'l'='NATURAL'
'by' acts as a link.
(Other definitions for natural that I've seen before include "certain to succeed" , "without man's involvement" , "Reason for death when not suspicious" , "Inborn; unaffected" , "Normal; off-white" .)