Move steadily, like canine in retreat (4)
I believe the answer is:
flow
'move steadily' is the definition.
(I've seen this before)
'canine in retreat' is the wordplay.
'canine' becomes 'wolf' (wolf is a kind of canine).
'in retreat' says the letters should be written in reverse.
'wolf' back-to-front is 'FLOW'.
'like' acts as a link.
(Other definitions for flow that I've seen before include "Current" , "Uninterrupted stream" , "Well forth" , "Wolf (anag.)" , "Move along as a stream" .)