British have roast (5)
I believe the answer is:
brown
'roast' is the definition.
(thesaurus)
'british have' is the wordplay.
'british' becomes 'br'.
'have' becomes 'own' ('own' can be a synonym of 'have').
'br'+'own'='BROWN'
(Other definitions for brown that I've seen before include "Capability" , "Suntanned; sort of bear/study" , "Colour - grill lightly" , "Mixture of red, yellow and blue" , "Colour (but not that of his box!)" .)