She won't let you get away with it (3)
I believe the answer is:
sue
'she' is the definition.
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for sue that I've seen before include "Susan (dim.)" , "Use to prosecute" , "Start proceedings against (someone)" , "Bring a legal action" , "Use to take to court" .)