Stayed to be declared sober (5)
I believe the answer is:
Here is my best explanation:
'sober' is the definition.
('staid' can be a synonym of 'sober')
'stayed to be declared' is the subsidiary indication.
'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 "Conventional (character)", "Calm, respectable and unadventurous", "Stiff; serious minded", "Restrained (in character)", "Dully unadventurous", "Sober and sedate", "Sedate, unadventurous", "Stuffy, traditional", "Proper; sedate" and "Unadventurous, dull".)