Virtuous but cheats badly (6)
I believe the answer is:
chaste
'virtuous' is the definition.
(associated in meaning)
'cheats badly' is the wordplay.
'badly' indicates anagramming the letters.
'cheats' with letters rearranged gives 'CHASTE'.
'but' acts as a link.
(Other definitions for chaste that I've seen before include "Undefiled" , "Modest and virtuous" , "She-cat could be virtuous" , "Everlasting" , "Showing virtue of kind" .)