Cause senora to be upset (6)
I believe the answer is:
reason
'cause' is the definition.
(I've seen this before)
'senora to be upset' is the wordplay.
'to be upset' indicates anagramming the letters.
'senora' with letters rearranged gives 'REASON'.
(Other definitions for reason that I've seen before include "Logic of senora" , "use of wit" , "Explanation for some event" , "Logic, sense" , "Justification needed" .)