Nothing is included with prize rosette (4)
I believe the answer is:
zero
'nothing' is the definition.
(synonyms)
'included with prize rosette' is the wordplay.
'included' says the answer is hidden in the clue (I've seen 'including' mean this).
'ZERO' is hidden within 'with prize rosette'.
'is' acts as a link.
(Other definitions for zero that I've seen before include "The hour to leave" , "Lowest point" , "has no effect, in addition" , "value?" , "[NIX]" .)