Awareness of things moving behind one (7)
I believe the answer is:
insight
'awareness' is the definition.
(I've seen this before)
'things moving behind one' is the wordplay.
'moving' indicates an anagram (letters are moved around).
'behind' is a charade indicator (letters next to each other).
'one' becomes 'i' (Roman numeral).
'things' is an anagram of 'nsight'.
'nsight' after 'i' is 'INSIGHT'.
'of' is the link.
(Other definitions for insight that I've seen before include "Awareness" , "Enlightenment" , "Grasp" , "Deep understanding" , "Perceptiveness" .)