The most common and most likely answer to this crossword clue is the 3 plus 5 letter word RED ALERT
I've seen this crossword clue in Financial Times
R
E
D
A
L
E
R
T
More clues leading to the result RED ALERT
- Right to protect Queen touring valley in response to emergency
- In state of emergency, merchant about to hide Louise’s skirts
- Warning on valley: retweet
- Auditor’s studied skill about the French in a crisis situation
- State of readiness for crisis, right after wine and beer
- Deluge engulfing valley and river – action stations
- Angry porter right to provide a warning
- Warning related to switch under top of roof
- Warning of critical situation altered, changed after last of thunder
- About to walk back around west end of loch in a state of readiness
Buddy explains!
The straight part
We know that "Ultimate state of readiness" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case ultimate state of readiness = red alert.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.