A guest’s complaint? (4)

I believe the answer is:

ague

'complaint?' is the definition.
(ague is a kind of disease)

'a guest's' is the wordplay.
'guest's' becomes 'gue' (I can't justify this - if you can you should believe this answer much more).
'a'+'gue'='AGUE'

(Other definitions for ague that I've seen before include "Acute fever; shivering fit" , "Fit of shivering and shaking" , "nasty illness?" , "Fever (archaic)" , "Malarial fever or fit of shivering" .)

I've seen this clue in the Evening Standard.

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