Arrogant Ruth out of bed first (6)
I believe the answer is:
uppity
'arrogant' is the definition.
(I've seen this before)
'ruth out of bed first' is the wordplay.
'ruth' becomes 'pity' (synonyms).
'out of bed' becomes 'up' (synonyms).
'first' means one lot of letters go next to another.
'pity' after 'up' is 'UPPITY'.
(Other definitions for uppity that I've seen before include "attitude" , "Pert; haughty" , "Informally pert or arrogant" , "Not easily persuaded" , "In need of slapping down?" .)