The most common and most likely answer to this crossword clue is the 4 letter word BOOM
B
O
O
M
More clues leading to the result BOOM
- Express disapproval with mass roar
- Market upsurge or crash?
- Nautical spar that’s never bust?
- Report a time of prosperity
- To express disapproval of Mike leads to explosion
- Blair’s reported prosperity
- Sign of dissatisfaction with maiden’s bust may follow this
- Be critical of money in period of prosperity
- Barrier for prosperity
- Heads of big old organisations mainly flourish
Buddy explains!

The straight part
We know that "Nautical spar" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case nautical spar = boom.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 BOOM mean?
BOOM noun- A low-pitched, resonant sound, such as of an explosion.
- A rapid expansion or increase.
- One of the calls of certain monkeys or birds.
- To make a loud, hollow, resonant sound.
- (of speech) To exclaim with force, to shout, to thunder.
- To make something boom.
- To publicly praise.
- To rush with violence and noise, as a ship under a press of sail, before a free wind.
- Used to suggest the sound of an explosion.
- Used to suggest something happening suddenly and unexpectedly.
- A spar extending the foot of a sail; a spar rigged outboard from a ship's side to which boats are secured in harbour.
- A movable pole used to support a microphone or camera.
- A horizontal member of a crane or derrick, used for lifting.
- The longest element of a Yagi antenna, on which the other, smaller ones are transversally mounted.
- A floating barrier used to obstruct navigation, for military or other purposes; or used for the containment of an oil spill or to control the flow of logs from logging operations.
- A wishbone-shaped piece of windsurfing equipment.
- The section of the arm on a backhoe closest to the tractor.
- A gymnastics apparatus similar to a balance beam.
- To extend, or push, with a boom or pole.
- (usually with "up" or "down") To raise or lower with a crane boom.
- A period of prosperity, growth, progress, or high market activity.
- To flourish, grow, or progress.
- To cause to advance rapidly in price.