Dismantles abandoned nest feeling gloomy (6)

I believe the answer is:

dismal

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'gloomy' is the definition.
(I know that gloomy can be written as dismal)

I don't understand the rest of the clue.

(Other definitions for dismal that I've seen before include "Gloomy and depressing like winter weather" , "Pessimist -- is my jam mild? (anag)" , "Very disappointing" , "Sad, gloomy" , "Discouraging" .)

I've seen this clue in The Irish Times.

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