US bard can be ridiculous (6)
I believe the answer is:
absurd
'ridiculous' is the definition.
(synonyms)
'us bard can be' is the wordplay.
'can be' indicates an anagram.
'us'+'bard'='usbard'
'usbard' anagrammed gives 'ABSURD'.
(Other definitions for absurd that I've seen before include "irrational" , "Quite ridiculous, silly" , "Ridiculous, ludicrous" , "Highly illogical" , "'Derisory, cockeyed (6)'" .)