The most common and most likely answer to this crossword clue is the 8 letter word TECTONIC
T
E
C
T
O
N
I
C
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The straight part
We know that "Regarding building" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case regarding building = tectonic.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 TECTONIC mean?
TECTONIC adjective- Of or relating to construction or to architecture
- Structural
- Of, relating to, or caused by large-scale movements of the Earth's lithosphere
- Momentous, utter, vast