Crossword Genius

Chest: one heard having trouble with it? (6)

Ross

I believe the answer is:

coffer

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

'chest' is the definition.
(I know that coffer is a type of chest)

I don't understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for coffer that I've seen before include "safe" , "A large strong box for valuables" , "Strongbox" , "Small chest for keeping valuables" , "Money chest sounds like one with lung trouble" .)

I've seen this clue in The Times.
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