The most common and most likely answer to this crossword clue is the 5 letter word ROACH
I've seen this crossword clue in Financial Times
R
O
A
C
H
More clues leading to the result ROACH
- Fish from right cook with head removed
- Fabulous bird takes hour to eat a fish
- Fish in a butt
- Animal found in the water butt
- Old huntsman’s dog gripping duck in butt
- Final section of joint unfinished choral works
- American insect‘s joint end
- What’s left of joint account is donated to London arts venue
- Covent Garden welcomes a contralto, one with plenty of scales!
- Butt in reproachfully
Buddy explains!

The straight part
We know that "one with plenty of scales" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one with plenty of scales = roach.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 ROACH mean?
ROACH noun- Certain members of the fish family Cyprinidae, including:
- A cockroach.
- An extra curve of material added to the leech (aft edge) of a sail to increase the sail area.
- A kind of headdress worn by some of the indigenous peoples of North America.
- (smoking) Marijuana; cannabis used as a drug.
- (smoking) A butt of a marijuana cigarette.
- (smoking) The filter of a rolled cigarette or joint, made from card or paper.
- A bed or stratum of some mineral.
- Gritty or coarse rock; especially Portland stone or similar limestone.