Support wickedness, bumping off one in proximity (11)

'proximity' is the definition.
('propinquity' can be a synonym of 'proximity')

'support wickedness bumping off one' is the wordplay.
I cannot quite understand how this works, but
'support' could be 'prop' (prop is a kind of support) and 'prop' is located in the answer.
'one' could be 'i' (Roman numeral) and 'i' is found in the answer.
This may be the basis of clue (or it may be nonsense).

'in' acts as a link.