Stayed to be declared sober (5)
I believe the answer is:
staid
'sober' is the definition.
('staid' can be a synonym of 'sober')
'stayed to be declared' is the wordplay.
'to be declared' indicates a 'sounds like' (homophone) clue.
'stayed' is a homophone of 'STAID'.
(Other definitions for staid that I've seen before include "Sedate, unadventurous" , "Calm, respectable and unadventurous" , "Stiff; serious minded" , "Restrained (in character)" , "Unadventurous, dull" .)