Canadian's box of beer, whiskey, old and fine used during trip (3-4)

'canadian's box of beer' is the definition.
(Canadian slang for a box of 24 beer bottles)

'whiskey old and fine used during trip' is the wordplay.
'whiskey old' becomes 'wo' (this could be a standard abbreviation I've not previously seen).
'and' means one lot of letters go next to another.
'fine' becomes 'f' (abbreviation).
'used during' is an insertion indicator.
'trip' becomes 'tour' (a journey or expedition).
'wo'+'f'='wof'
'wof' placed into 'tour' is 'TWO-FOUR'.