The most common and most likely answer to this crossword clue is the 4 letter word ROAR
I've seen this crossword clue in The Daily Telegraph
R
O
A
R
More clues leading to the result ROAR
- Guffaw unrefined, by the sound of it?
- Big laugh from Bard uncovered
- The Speaker’s bitter cry
- 19 ends in disaster to a Republican
- Sound of biting scream
- Playing seconds from Johnny Cash: Cry! Cry! Cry!
- Beastly noise as rhino and alligator both cleared out
- Loud sound natural when heard?
- Shout in row after run
- Shout from nomad putting me off
Buddy explains!

The straight part
We know that "Shout" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case shout = roar.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 ROAR mean?
ROAR noun- A long, loud, deep shout, as of rage or laughter, made with the mouth wide open.
- The cry of the lion.
- The deep cry of the bull.
- A loud resounding noise.
- A show of strength or character.
- To make a loud, deep cry, especially from pain, anger, or other strong emotion.
- To laugh in a particularly loud manner.
- Of animals (especially the lion), to make a loud deep noise.
- Generally, of inanimate objects etc., to make a loud resounding noise.
- To proceed vigorously.
- To cry aloud; to proclaim loudly.
- To be boisterous; to be disorderly.
- To make a loud noise in breathing, as horses do when they have a certain disease.
- (North Midlands) to cry