Power on after Webers Centre shows a warning light (6)
I believe the answer is:
beacon
'a warning light' is the definition.
(I've seen this before)
'power on after webers centre' is the wordplay.
'power' becomes 'ac' (AC is an example).
'after' means one lot of letters go next to another.
'centre' indicates the central letters.
The central letters of 'webers' are 'be'.
'ac'+'on'='acon'
'acon' put after 'be' is 'BEACON'.
'shows' is the link.
(Other definitions for beacon that I've seen before include "Hilltop signal fire" , "Warning light on tower or hill" , "guidance" , "Navigational guide" , "Signal fire - signalling buoy" .)