Bachelor's pain (4)

I believe the answer is:

ache

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

'pain' is the definition.
(ache is a kind of pain)

'bachelor's' is the wordplay.
'ACHE' is hidden in amongst the letters.
But, I am not sure how the hidden word is indicated.

Can you help me to learn more?

(Other definitions for ache that I've seen before include "Cause pain" , "agony" , "Dull continuous pain" , "Suffer dull pain" , "anguish" .)

I've seen this clue in The Mirror.

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