My dad, drunk around one, or noon! (6)
I believe the answer is:
Here is my best explanation:
'noon' is the definition.
('midday' can be a synonym of 'noon')
'my dad drunk around one' is the wordplay.
'drunk' indicates an anagram.
'around' indicates putting letters inside.
'one' becomes 'i' (Roman numeral).
'mydad' with letters rearranged gives 'mdday'.
'mdday' going around 'i' is 'MIDDAY'.
'or' is the link.