Consider parking with warning light, no reversing (6)
I believe the answer is:
ponder
'consider' is the definition.
(I know that consider is a more specific form of the action ponder)
'parking with warning light no reversing' is the wordplay.
'parking' becomes 'p' (abbreviation on road signs).
'with' is a charade indicator (letters next to each other).
'warning light' becomes 'red' (in traffic lights).
'reversing' says the letters should be written in reverse.
'red'+'no'='redno'
'redno' written backwards gives 'onder'.
'p'+'onder'='PONDER'
(Other definitions for ponder that I've seen before include "Weigh in the mind" , "Ruminate, mull over" , "Muse" , "Contemplate, think over" , "4 down" .)