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Grumpy, like to go up and hit the sack by twelve latest (9)

Ross

I believe the answer is:

saturnine

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(Other definitions for saturnine that I've seen before include "dismal" , "may be brooding" , "Morose looking" , "offering little amusement" , "A rust nine chnage to be grave and gloomy" .)

I've seen this clue in The Hindu.
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