Always turn right to turn back (6)
I believe the answer is:
revert
'to turn back' is the definition.
(synonyms)
'always turn right' is the wordplay.
'always' becomes 'ever' (synonyms).
'turn' says the letters should be written in reverse.
'right' becomes 'rt' (abbreviation as in Rt Hon- the Right Honourable).
'ever' in reverse letter order is 'reve'.
'reve'+'rt'='REVERT'
(Other definitions for revert that I've seen before include "Return to former state (6)" , "Regress" , "Return to (a previous state)" , "Backslide, return to former state" , "Turn back" .)