The most common and most likely answer to this crossword clue is the 4 letter word DOOM
I've seen this crossword clue in Independent
D
O
O
M
More clues leading to the result DOOM
- State of mind upset, getting judgment
- Pronounce judgement on tenor after rising
- Final judgement is indicative, say, in review
- Downfall of party over ending of Thatcherism
- Fate of party, a short time after upset
- Fate to make love with male
- Humour about the Last Trump
- Inevitable annihilation has war department circling round in a spin
- Low returns on diamonds must mean inevitable ruin
- Downfall makes temper return
Buddy explains!

The straight part
We know that "Inevitable annihilation" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case inevitable annihilation = doom.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 DOOM mean?
DOOM noun- Destiny, especially terrible.
- An undesirable fate; an impending severe occurrence or danger that seems inevitable.
- A feeling of danger, impending danger, darkness or despair.
- A law.
- A judgment or decision.
- A sentence or penalty for illegal behaviour.
- Death.
- (sometimes capitalized) The Last Judgment; or, an artistic representation thereof.
- To pronounce sentence or judgment on; to condemn.
- To destine; to fix irrevocably the ill fate of.
- To judge; to estimate or determine as a judge.
- To ordain as a penalty; hence, to mulct or fine.
- To assess a tax upon, by estimate or at discretion.