She has one earl in fits (7)
I believe the answer is:
eleanor
'she has one earl in fits' is the definition.
I can't judge whether this definition defines the answer.
'she has one earl' is the wordplay.
'she' becomes 'leanor' ().
'has' is a charade indicator (letters next to each other).
'one earl' becomes 'e'.
'leanor' put after 'e' is 'ELEANOR'.
Can you help me to learn more?
(Other definitions for eleanor that I've seen before include "Consort of Henry II" , "Edward the First's queen" , "woman" , "Wife of Henry II" , "girl" .)