The most common and most likely answer to this crossword clue is the 8 letter word CYANOSIS
I've seen this crossword clue in The Guardian
C
Y
A
N
O
S
I
S
Buddy explains!
The straight part
We know that "a result of oxygen deficiency" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case a result of oxygen deficiency = cyanosis.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 CYANOSIS mean?
CYANOSIS noun- A blue discolouration of the skin due to the circulation of blood low in oxygen.