Sober, Dad dropped off spaghetti? (5)
I believe the answer is:
staid
'sober' is the definition.
(synonyms)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for staid that I've seen before include "Sedate; dull" , "Conventional (character)" , "Sober, grave" , "Stiff; serious minded" , "Calm, respectable and unadventurous" .)