Her reason is disturbed (6)
I believe the answer is:
senora
'her' is the definition.
I can't tell whether this defines the answer.
'reason is disturbed' is the wordplay.
'is disturbed' indicates anagramming the letters (the order of letters is disturbed).
'reason' anagrammed gives 'SENORA'.
Can you help me to learn more?
(Other definitions for senora that I've seen before include "A married woman in Spain - stands to reason" , "Lady of Spain" , "Foreign lady; reason (anag.)" , "Mrs or madam (Spanish)" , "Reason with a Spanish woman, probably married" .)