Move back. It’s right behind (4)
I believe the answer is:
stir
'move' is the definition.
(stir is a kind of move)
'back it's right behind' is the wordplay.
'back' says the letters should be written backwards.
'right' becomes 'r' (common abbreviation).
'behind' is a charade indicator (letters next to each other).
'its' written backwards gives 'sti'.
'sti'+'r'='STIR'
(Other definitions for stir that I've seen before include "Agitate; wake from sleep" , "Move around and mix thoroughly" , "Produce disorder < , wake up" , "bird" , "riot" .)