The most common and most likely answer to this crossword clue is the 8 letter word THRUSTER
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Buddy explains!
The straight part
We know that "One bringing the end of Caesar, ruddy penetrative?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one bringing the end of caesar, ruddy penetrative? = thruster.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 THRUSTER mean?
THRUSTER noun- One who thrusts, who pushes or stabs.
- A device for propelling an object, especially a spacecraft or a ship (marine vessel).
- A bow thruster or a stern thruster.
- A surfboard (usually a shortboard) with three fins of approximately equal size, one centred at the back, one on each side about 25cm forward and out near the rails.
- An ambitious, driven person; a go-getter.