The most common and most likely answer to this crossword clue is the 8 letter word MARBLING
I've seen this crossword clue in Financial Times
M
A
R
B
L
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G
More clues leading to the result MARBLING
- Streaks of butter round black fish
- Spoil jewellery, adding mottled effect
- Mottled appearance to have a bad effect on glitzy stuff
- Mottled effect is blight on jewellery
- Damage on jewellery that gives a streaky appearance
- Batter around second-rate fish showing veiny appearance
- Twisted arm jewelry's mottled pattern
Buddy explains!

The straight part
We know that "Mottled appearance" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case mottled appearance = marbling.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 MARBLING mean?
MARBLING verb- To cause (something to have) the streaked or swirled appearance of certain types of marble, for example by mixing viscous ingredients incompletely, or by applying paint or other colorants unevenly.
- To get or have the streaked or swirled appearance of certain types of marble, for example due to the incomplete mixing of viscous ingredients, or the uneven application of paint or other colorants.
- To cause meat, usually beef, pork, or lamb, to be interlaced with fat so that its appearance resembles that of marble.
- (of meat, especially beef) To become interlaced with fat; (of fat) to interlace through meat.
- (by extension) To lace or be laced throughout.
- A mottled or streaky appearance
- The process of adding such an appearance, especially as a decoration