Bully essentially harassed teen in kind (7)
I believe the answer is:
lenient
'kind' is the definition.
(thesaurus)
'bully essentially harassed teen in' is the wordplay.
'essentially' indicates the central letters.
'harassed' indicates anagramming the letters.
The central letter of 'bully' is 'l'.
'teen'+'in'='teenin'
'teenin' is an anagram of 'enient'.
'l'+'enient'='LENIENT'
(Other definitions for lenient that I've seen before include "Soft-hearted" , "'Indulgent, easy (7)'" , "Forbearing" , "Not severe, merciful" , "Tolerant, rather than strict" .)