Standard paving stone (4)
I believe the answer is:
flag
This clue is a double definition.
'standard' is the first definition.
(I've seen this in another clue)
'paving stone' is the second definition.
(flag is a kind of paving stone)
(Other definitions for flag that I've seen before include "Get weary" , "appears to lose energy" , "Colours a paving stone" , "Standard; tire" , "National standard" .)