Anger that smoulders in RC service? (7)
I believe the answer is:
incense
This clue is a double definition.
'anger' is the first definition.
(incensing is a kind of angering)
'that smoulders in rc service?' is the second definition.
(a Roman Catholic service might burn incense)
(Other definitions for incense that I've seen before include "A High Church feature" , "Greatly anger; perfume" , "To outrage" , "Send bananas" , "Anger - holy smoke!" .)