It says that the entries aren't necessarily real words so I think you just work out the definitions and write in the letters left after you take out the word 'rose' from each one.
For the other italic clues on the basis of removing the word "ROSE" 28a "Kerosene" leaves you with kene - this a print error and the clue should be in italics! 5d "Morosley" leaves you with moly - good luck - can't get the clue of the week though!