The most common and most likely answer to this crossword clue is the 8 letter word UNDERLAY
I've seen this crossword clue in The Sunday Telegraph
U
N
D
E
R
L
A
Y
Buddy explains!
The straight part
We know that "Was the cause of something/initially floored" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case was the cause of something/initially floored = underlay.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 UNDERLAY mean?
UNDERLAY verb- To lay (something) underneath something else; to put under.
- To provide a support for something; to raise or support by something laid under.
- To put a tap on (a shoe).
- (of a vein, fault, or lode) To incline from the vertical.
- To lie in a position directly beneath.
- To lie under or beneath.
- To serve as a basis of; form the foundation of.
- To be subject to; be liable to answer, as a charge or challenge.
- To underlay.
- A layer (of earth, etc.) that lies under another; substratum.
- A soft floor covering that lies under a carpet.
- Anything that is underlaid.
- A piece of paper pasted under woodcuts, stereotype plates, etc. in a form, to bring them up to the necessary level for printing.
- Lyrics; or more specifically, the way in which lyrics are assigned to musical notes.