The most common and most likely answer to this crossword clue is the 10 letter word ISOCHRONAL
I've seen this crossword clue in The Daily Telegraph
I
S
O
C
H
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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 ISOCHRONAL mean?
ISOCHRONAL adjective- Having the same duration.
- Happening at regular periods; isochronous, periodic.
- (of data) Time-dependent.