Kesha's style is rock (5)
I believe the answer is:
shake
'is rock' is the definition.
(I've seen this before)
'kesha's style' is the wordplay.
'style' indicates an anagram (style can mean to shape or design).
'kesha' is an anagram of 'SHAKE'.
(Other definitions for shake that I've seen before include "Tremble, quake" , "Quiver" , "Frothy milk drink" , "Shiver" , "Vibrate; drink" .)