Keep it near, as needed (6)
I believe the answer is:
retain
'keep' is the definition.
(I know that keep is a type of sustain)
'it near as needed' is the wordplay.
'it near' can be anagrammed to 'RETAIN'.
However, I'm not sure how this is indicated.
Can you help me to learn more?
(Other definitions for retain that I've seen before include "Keep, hold on to something" , "Not relinquish" , "Hold on to or employ counsel" , "Keep in place" , "Keep; remember" .)