Expose shabby characters, suggesting this is no longer accepted (7)
I believe the answer is:
outworn
'characters suggesting this is no longer accepted' is the definition.
The definition suggests a singular noun but the answer is not.
'expose shabby' is the wordplay.
'expose' becomes 'out' (to out someone is to expose them).
'shabby' becomes 'worn' (similar in meaning).
'out'+'worn'='OUTWORN'
Can you help me to learn more?
(Other definitions for outworn that I've seen before include "Old, exhausted or no longer used as dress" , "Obsolete, dated" , "Old-fashioned" , "Out of date" , "Jaded" .)