The most common and most likely answer to this crossword clue is the 4 letter word TOLL
I've seen this crossword clue in Financial Times
T
O
L
L
Buddy explains!

The straight part
We know that "Rate/sound as a bell" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case rate/sound as a bell = toll.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 TOLL mean?
TOLL noun- Loss or damage incurred through a disaster.
- A fee paid for some liberty or privilege, particularly for the privilege of passing over a bridge or on a highway, or for that of vending goods in a fair, market, etc.
- A fee for using any kind of material processing service.
- A tollbooth.
- A liberty to buy and sell within the bounds of a manor.
- A portion of grain taken by a miller as a compensation for grinding.
- To impose a fee for the use of.
- To levy a toll on (someone or something).
- To take as a toll.
- To pay a toll or tallage.
- The act or sound of tolling
- To ring (a bell) slowly and repeatedly.
- To summon by ringing a bell.
- To announce by tolling.
- To draw; pull; tug; drag.
- To tear in pieces.
- To draw; entice; invite; allure.
- To lure with bait; tole (especially, fish and animals).
- To take away; to vacate; to annul.
- To suspend.