The most common and most likely answer to this crossword clue is the 8 letter word HATCHERY
I've seen this crossword clue in Financial Times
H
A
T
C
H
E
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Y
More clues leading to the result HATCHERY
Buddy explains!
The straight part
We know that "Originally carp here" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case originally carp here = hatchery.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 HATCHERY mean?
HATCHERY noun- A facility where eggs are hatched under artificial conditions, especially those of fish or poultry.