Songsmith, essentially mischievous and egocentric (7)
I believe the answer is:
selfish
'egocentric' is the definition.
(thesaurus)
'songsmith essentially mischievous' is the wordplay.
'essentially' means to look at the middle letters.
'mischievous' becomes 'elfish' ('elfish' can be a synonym of 'mischievous').
The centre of 'songsmith' is 's'.
's'+'elfish'='SELFISH'
'and' is the link.
(Other definitions for selfish that I've seen before include "inconsiderate" , "Concerned chiefly with one's own interests" , "without consideration" , "Egocentric - greedy" , "Concerned only with oneself" .)