Russian source coming west as requested (2,5)
I believe the answer is:
to order
'as requested' is the definition.
(as in items made to order)
'russian source coming west' is the wordplay.
'russian' becomes 'red' (red can informally mean communist).
'source' becomes 'root' (both can mean the origin of something).
'coming west' is a reversal indicator (letters go right to left or 'east to west').
'red'+'root'='redroot'
'redroot' reversed gives 'TO ORDER'.
(Other definitions for to order that I've seen before include "as required" , "In fulfilment of an instruction" , "In accordance with specification" , "As specified" .)