Sailors send a signal up limiting distress (7)

I believe the answer is:

sadness

I'm a little stuck... Click here to teach me more about this clue!

'distress' is the definition.
(I've seen this before)

'sailors send a signal up limiting' is the wordplay.
'SADNESS' is hidden back-to-front in amongst the letters.
However, I'm unsure how the hidden word is indicated.

Can you help me to learn more?

(Other definitions for sadness that I've seen before include "Despondency" , "Misery" , "Sorrowfulness" , "Unhappy feeling" , "gravity" .)

I've seen this clue in The Telegraph.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.