Be furious seeing gratuities raised (4)
I believe the answer is:
spit
'be furious' is the definition.
(I've seen this before)
'gratuities raised' is the wordplay.
'gratuities' becomes 'tips' ('tip' can be a synonym of 'gratuity').
'raised' is a reversal indicator (going up in a down clue).
'tips' backwards is 'SPIT'.
'seeing' is the link.
(Other definitions for spit that I've seen before include "Coastal feature, tongue of sand" , "double, perhaps" , "Narrow strip of land projecting into the sea" , "Rotisserie" , "Expectorate on the tongue of land" .)