In flipping list, police showing flasher in road (9)
I believe the answer is:
indicator
'flasher in road' is the definition.
'in flipping list police' is the wordplay.
'flipping' says the letters should be written in reverse.
'list' becomes 'rota' (rota is a kind of list**).
'police' becomes 'cid'.
'rota'+'cid'='rotacid'
'rotacid' reversed gives 'dicator'.
'in'+'dicator'='INDICATOR'
'showing' is the link.
(Other definitions for indicator that I've seen before include "This will show" , "shower" , "Station information board" , "Gauge, meter" , "Pointer" .)