The most common and most likely answer to this crossword clue is the 6 letter word BRUISE
I've seen this crossword clue in The Daily Telegraph
B
R
U
I
S
E
More clues leading to the result BRUISE
- Is preparing to speak out, causing hurt
- Pound of tea and coffee picked up?
- Mark is busier at work
- Plots out loud to cause injury
- Bishop, one ensnared by trick and upset
- Mark puts the kettle on, we hear
- Fake rubies could cause skin discoloration
- “Teas?” said Mark
- Mark drinks audibly
- Surface discoloration may come from tea and coffee, it’s said
Buddy explains!

The straight part
We know that "skin discoloration" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case skin discoloration = bruise.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 BRUISE mean?
BRUISE noun- A purplish mark on the skin due to leakage of blood from capillaries under the surface that have been damaged by a blow.
- A dark mark on fruit or vegetables caused by a blow to the surface.
- To strike (a person), originally with something flat or heavy, but now specifically in such a way as to discolour the skin without breaking it.
- To damage the skin of (fruit or vegetables), in an analogous way.
- Of fruit or vegetables, to gain bruises through being handled roughly.
- To become bruised.
- To fight with the fists; to box.