The most common and most likely answer to this crossword clue is the 8 letter word SUBSONIC
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More clues leading to the result SUBSONIC
- Reserve’s virtually shelved, being not the quickest
- Such a speed’s not shocking, seeing warships nearly stranded in the Antarctic?
- Navy vessels almost all kept in readiness, not like the fastest jets
- Reserve’s on ice mostly, not matching Yeager’s achievement?
- Relatively slow U-boats laid up unfinished
- Hoagies in the freezer mostly? Not so fast
Buddy explains!

The straight part
We know that "not like the fastest jets" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case not like the fastest jets = subsonic.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 SUBSONIC mean?
SUBSONIC noun- An aircraft whose maximum speed is less than the speed of sound
- (of a sound, scientific) having a frequency too low to be audible
- (of a sound, literary) very quiet, almost inaudible
- (of a speed) less than the speed of sound (in the same medium, and at the same temperature and pressure)
- (of a flow) with a Mach number such that 0.3 < Ma < 0.8 (approximately - the exact limits vary between sources)