A ton wasted with credit diminishing (10)
I believe the answer is:
detraction
'a ton wasted with credit diminishing' is the definition.
I can't tell whether this defines the answer.
'a ton wasted with credit' is the wordplay.
'wasted with' is an anagram indicator.
'a'+'ton'='aton'
'aton' mixed up with 'credit' gives 'DETRACTION'.
(Other definitions for detraction that I've seen before include "Slander" , "Disparagement" .)