Get angry note dictated by leftist (3,3)
I believe the answer is:
see red
'get angry' is the definition.
(synonyms)
'note dictated by leftist' is the wordplay.
'note' becomes 'c' (musical note).
'dictated' indicates a 'sounds like' (homophone) clue (how it might sound if someone dictated it).
'by' means one lot of letters go next to another.
'leftist' becomes 'red' (red can informally mean communist).
'c' is a homophone of 'see'.
'see'+'red'='SEE RED'
(Other definitions for see red that I've seen before include "Lose temper like angry bull" , "Be suddenly angry - like bull?" , "Be annoyed" , "Become angry like bull" , "Burst a blood vessel" .)