Surrounded by a shadowy reflection (4)
I believe the answer is:
amid
'surrounded by' is the definition.
(I've seen this before)
'a shadowy reflection' is the wordplay.
'shadowy' becomes 'dim' ('dim' can be a synonym of 'shadowy').
'reflection' says the letters should be written backwards.
'dim' in reverse letter order is 'mid'.
'a'+'mid'='AMID'
(Other definitions for amid that I've seen before include "A dim sort of preposition" , "In the middle of" , "Amongst" , "Surrounded by" , "In the course of" .)