Sibling has run out? Damn! (6)

I believe the answer is:

bother

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

'damn' is the definition.
(both are expressions of annoyance)

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

(Other definitions for bother that I've seen before include "Discommode, annoy" , "Irritate - concern oneself" , "Fuss and irritant" , "Badger" , "Annoy or pester" .)

I've seen this clue in The Times.

Want a hint initially instead of a full solution? Install my app