Case of tequila? Cheers and cheerio! (2-2)
I believe the answer is:
ta-ta
'cheerio' is the definition.
(I've seen this before)
'case of tequila? cheers' is the wordplay.
'case of' suggests removing the centre (like emptying a case).
'cheers' becomes 'ta' (both can informally mean thank you).
'tequila' with its middle taken out is 'ta'.
'ta'+'ta'='TA-TA'
'and' acts as a link.
(Other definitions for ta-ta that I've seen before include "A Farewell" , "Cheerio" , "Bye!" , "Adieu" , "Bye-bye" .)