Be in poor health - drink needed, we hear (3)

I believe the answer is:

ail

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

'be in poor health' is the definition.
(I've seen this in another clue)

I cannot understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for ail that I've seen before include "Afflict; suffer" , "upset" , "Be unwell, feel poorly" , "Become sick" , "Cause to feel indisposed" .)

I've seen this clue in The Irish News.

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.