She gets angry when Amy's Yankee deserts (5)
I believe the answer is:
madam
'she gets angry' is the definition.
I can't judge whether this definition defines the answer.
'when amy's yankee deserts' is the wordplay.
'when' becomes 'mad' (I can't explain this - if you can you should believe this answer much more).
'yankee' becomes 'Y' (phonetic alphabet: alpha, bravo, charlie etc.).
'deserts' indicates named letters should be taken away.
'amy' with 'y' taken out is 'am'.
'mad'+'am'='MADAM'
Can you help me to learn more?
(Other definitions for madam that I've seen before include "Conceited girl (colloq.)" , "Make wildly happy" , "Woman running a brothel" , "Stuck-up girl" , "Courteous form of address to a woman" .)