The most common and most likely answer to this crossword clue is the 11 letter word LARGE-SCALE
I've seen this crossword clue in The Times
L
A
R
G
E
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S
C
A
L
E
More clues leading to the result LARGE-SCALE
Buddy explains!
The straight part
We know that "comprehensive" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case comprehensive = large-scale.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 LARGE-SCALE mean?
LARGE-SCALE adjective- Large in amount, scope or extent.
- (of a map or image) Drawn large so as to show detail.