Crossword Genius

Resident mostly irritable about curtailed trip (9)

Ross

I believe the answer is:

sojourner

'resident' is the definition.
(I know that sojourner is a type of resident)

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

(Other definitions for sojourner that I've seen before include "Temporary resident" , "25 28 [MARS LANDER]" .)

I've seen this clue in The Independent.
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