Spotted communist and went bananas (3,3)
I believe the answer is:
saw red
'went bananas' is the definition.
'spotted communist' is the wordplay.
'spotted' becomes 'saw' (I've seen this in other clues).
'communist' becomes 'red' (red is a kind of communist).
'saw'+'red'='SAW RED'
'and' is the link.
(Other definitions for saw red that I've seen before include "(In anger) totally lost control" , "Grew furious" .)