Still acts strangely about it on return (6)
I believe the answer is:
static
'still' is the definition.
(static can mean still or not moving)
'acts strangely about it on return' is the wordplay.
'strangely' is an anagram indicator.
'about' indicates putting letters inside.
'on return' shows that the letters should be reversed in order.
'it' back-to-front is 'ti'.
'acts' with letters rearranged gives 'stac'.
'stac' going around 'ti' is 'STATIC'.
(Other definitions for static that I've seen before include "Atmospheric disturbance" , "Changeless" , "Unmoving, unchanging" , "Motionless like certain electricity" , "disturbing thing" .)