Warning light in Wokingham, Berks (5)
I believe the answer is:
amber
'warning light' is the definition.
(I've seen this before)
'in wokingham berks' is the wordplay.
'in' indicates the answer is hidden within the clue.
'AMBER' can be found hidden inside 'wokingham berks'.
(Other definitions for amber that I've seen before include "Yellow, translucent fossil resin" , "Traffic light colour" , "Medium to dark brownish-yellow colour" , "The traffic-light between red and green" , "Middle light" .)