Sign spotted in time to turn back (5)
I believe the answer is:
totem
'sign' is the definition.
(I've seen this before)
'spotted in time to turn back' is the wordplay.
'spotted in' says the answer is hidden in the clue.
'back' is a reversal indicator.
'metot' can be found hidden inside 'time to turn'.
'metot' written backwards gives 'TOTEM'.
(Other definitions for totem that I've seen before include "Sort of pole" , "symbolic animal" , "Venerated object" , "Emblematic animal or object" , "charming symbol, say" .)