Distinctly cunning around stringed instrument (7)
I believe the answer is:
sharply
'distinctly' is the definition.
(thesaurus)
'cunning around stringed instrument' is the wordplay.
'cunning' becomes 'sly' (synonyms).
'around' indicates putting letters inside.
'stringed instrument' becomes 'harp' (harp is a kind of stringed instrument).
'sly' enclosing 'harp' is 'SHARPLY'.
(Other definitions for sharply that I've seen before include "Critically" , "Very suddenly and to a great degree" , "Crisply" , "Punctually" , "In an aggressive manner" .)