The most common and most likely answer to this crossword clue is the 5 letter word SHOUT
I've seen this crossword clue in Financial Times
S
H
O
U
T
More clues leading to the result SHOUT
Buddy explains!

The straight part
We know that "the opposite?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case the opposite? = shout.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 SHOUT mean?
SHOUT noun- A loud burst of voice or voices; a violent and sudden outcry, especially that of a multitude expressing joy, triumph, exultation, anger, or animated courage.
- A round of drinks in a pub; the turn to pay the shot or scot; an act of paying for a round of drinks.
- A call-out for an emergency services team.
- A greeting, name-check or other mention, for example on a radio or TV programme.
- To utter a sudden and loud cry, as in joy, triumph, exultation or anger, or to attract attention, to animate others, etc.
- To utter with a shout; to cry; to shout out
- To pay for food, drink or entertainment for others.
- To post a text message (for example, email) in upper case, regarded as the electronic messaging equivalent of oral shouting.
- To treat with shouts or clamor.
- A light flat-bottomed boat used in duck-shooting.