Surrounded by support, receiving millions (4)
I believe the answer is:
amid
'surrounded by' is the definition.
(amid means among or surrounded by)
'support receiving millions' is the wordplay.
'support' becomes 'aid' (to aid is to help or support).
'receiving' is an insertion indicator.
'millions' becomes 'm' (abbreviation).
'aid' placed around 'm' is 'AMID'.
(Other definitions for amid that I've seen before include "Amongst" , "In the course of" , "Within" , "In the thick of" , "In the centre of" .)