I can’t believe that incense! (4,5)
I believe the answer is:
holy smoke
I'm afraid I can't even guess how this answer relates to the clue.
Can you help me to learn more?
(Other definitions for holy smoke that I've seen before include "I'm surprised" , "What emerges at the choosing of a Pope?" , "sign of election result" , "Mild oath (product of a censer?)" , "The product of burning incense - gosh!" .)