Look to go back half a mile (4)
I believe the answer is:
ogle
'look' is the definition.
(I know that ogle is a more specific form of the action look)
'go back half a mile' is the wordplay.
'back' says the letters should be written backwards.
'half a' means to take half the letters.
'go' back-to-front is 'og'.
'mile' cut in half is 'le'.
'og'+'le'='OGLE'
'to' is the link.
(Other definitions for ogle that I've seen before include "Look at lecherously" , "Close scrutiny" , "View lecherously" , "Cast flirtatious glance at" , "Look at with amorous intentions" .)