She's the one a male's upset about (6)
I believe the answer is:
amelia
'she's' is the definition.
'one a male's upset about' is the wordplay.
'one' becomes 'i' (Roman numeral).
'upset' is an anagram indicator.
'about' becomes 'a' (abbreviation in Chambers).
'i'+'male'='imale'
'imale' anagrammed gives 'ameli'.
'ameli'+'a'='AMELIA'
'the' acts as a link.
(Other definitions for amelia that I've seen before include "I, a male (anag) - a woman" , "-- Earhart, aviator" , "famous pilot" , "Fielding heroine" , "-- Earhart, US aviation pioneer" .)