The most common and most likely answer to this crossword clue is the 7 letter word BRANDED
I've seen this crossword clue in Financial Times
B
R
A
N
D
E
D
Buddy explains!

The straight part
We know that "discredited" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case discredited = branded.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does BRANDED mean?
BRANDED verb- To burn the flesh with a hot iron, either as a marker (for criminals, slaves etc.) or to cauterise a wound.
- To mark (especially cattle) with a brand as proof of ownership.
- To make an indelible impression on the memory or senses.
- To stigmatize, label (someone).
- To associate a product or service with a trademark or other name and related images.