Rita's indisposed but out of bed (5)
I believe the answer is:
astir
'out of bed' is the definition.
(synonyms)
'rita's indisposed' is the wordplay.
'indisposed' is an anagram indicator.
'ritas' is an anagram of 'ASTIR'.
'but' is the link.
(Other definitions for astir that I've seen before include "Excitedly moving" , "abroad" , "This isn't still" , "Up and about -- is art (anag)" , "Starting to move" .)