Drink to one's health (5)
I believe the answer is:
toast
'drink to one's health' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for toast that I've seen before include "Drink to someone" , "Drink to the healt of" , "A bit of a bloomer, possibly" , "Formally drink a health" , "Brown under a grill" .)