Alpha males upset by a single buttercup (7)
I believe the answer is:
anemone
'single buttercup' is the definition.
The definition and answer can be both plants as well as being singular nouns.
Maybe you can see a link between them that I can't see?
'alpha males upset by a' is the wordplay.
'alpha' becomes 'a' (phonetic alphabet: alpha, bravo, charlie etc.).
'males' becomes 'men' (man is a kind of male).
'upset' says the letters should be written backwards.
'by' is a charade indicator (letters next to each other).
'a' becomes 'one'.
'men' backwards is 'nem'.
'a'+'nem'+'one'='ANEMONE'
Can you help me to learn more?
(Other definitions for anemone that I've seen before include "Plant; sea creature" , "Woodland plant, eg the windflower" , "Flower; marine polyp" , "White woodland flower" , "Buttercup-like flower or sea animal" .)