Drink to us tipsily on Tuesday (5)
I believe the answer is:
stout
'drink' is the definition.
(type of beer)
'to us tipsily on tuesday' is the wordplay.
'tipsily' indicates an anagram (in a drunk or tipsy way).
'on' is an insertion indicator (as in clothing 'on' a person).
'tuesday' becomes 't'.
'us' is an anagram of 'su'.
'to' going within 'su' is 'stou'.
'stou'+'t'='STOUT'
(Other definitions for stout that I've seen before include "Overweight; porter" , "Resolute" , "Dark beer for the rather fat" , "Rather fat, drink" , "Portly - type of dark beer" .)