She's some ballerina making a comeback (4)
I believe the answer is:
ella
'she's' is the definition.
(I've seen this before)
'some ballerina making a comeback' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'making a comeback' says the letters should be written backwards.
'alle' can be found hidden inside 'ballerina'.
'alle' back-to-front is 'ELLA'.
(Other definitions for ella that I've seen before include "- - Fitzgerald (mus.)" , "Miss" , "- Wheeler Wilcox, US poet" , "Girl" , "Diminutive of Eleanor" .)