Hit twice, your health! (4-4)
I believe the answer is:
chin-chin
'your health' is the definition.
(both might be said when raising a toast)
'hit twice' is the wordplay.
'hit' becomes 'chin' (informal term meaning to punch someone's chin).
'twice' indicates the doubling of some letters.
'chin' doubled is 'CHIN-CHIN'.
(Other definitions for chin-chin that I've seen before include "good health ..." , "Cheers, bottoms up" , "Down the hatch!" .)