Counterfeit letter brings disgrace (5)
I believe the answer is:
shame
'disgrace' is the definition.
(I know that disgrace can be written as shame)
'counterfeit letter' is the wordplay.
'counterfeit' becomes 'sham' (sham is a kind of counterfeit).
'letter' becomes 'e' ().
'sham'+'e'='SHAME'
'brings' is the link.
(Other definitions for shame that I've seen before include "scandal" , "Discredit - ignominy" , "pity!" , "Disgrace, ignominy" , "Feeling of humiliation" .)