One cab's weird warning light (6)
I believe the answer is:
beacon
'warning light' is the definition.
(I've seen this before)
'one cab's weird' is the wordplay.
'weird' indicates anagramming the letters.
'one'+'cab'='onecab'
'onecab' is an anagram of 'BEACON'.
(Other definitions for beacon that I've seen before include "Prominent light on a hill" , "Directional transmitter" , "Fire on a hill, lit as a signal" , "Guiding light?" , "Warning fire or signal" .)