Cheers excessive order in various pubs (7,2)
I believe the answer is:
bottoms up
'cheers' is the definition.
(both can be said before having a drink)
'excessive order in various pubs' is the wordplay.
'excessive' becomes 'ott' (short for 'over the top').
'order' becomes 'om' (Order of Merit).
'in' means one lot of letters goes inside another.
'various' indicates an anagram.
'ott'+'om'='ottom'
'pubs' anagrammed gives 'bsup'.
'ottom' put within 'bsup' is 'BOTTOMS UP'.
(Other definitions for bottoms up that I've seen before include "down it goes!" , "Cheers!" , "Down the hatch!" , "Toast" , "Your good health!" .)