Cadger is source of shame (8)
I believe the answer is:
disgrace
'shame' is the definition.
(I know that shame can be written as disgrace)
'cadger is source of' is the wordplay.
'source of' indicates an anagram.
'cadger'+'is'='cadgeris'
'cadgeris' with letters rearranged gives 'DISGRACE'.
(Other definitions for disgrace that I've seen before include "Loss of honour" , "Shame or loss of respect" , "Loss of reputation or respect" , "Loss of reputation as the result of dishonourable action" , "scandalous" .)