Cook with right hop kiln (5)
I believe the answer is:
Here is my best explanation:
'cook' is the definition.
(roasting is a kind of cooking)
'with right hop kiln' is the subsidiary indication.
'with' says to put letters next to each other.
'right' becomes 'r' (common abbreviation).
'hop kiln' becomes 'oast' (I've seen this before).
'r' put next to 'oast' is 'roast'.
(Other definitions for roast that I've seen before include "Tear to pieces", "Reprimand severely", "Get hot", "Sunday tradition", "& 3 Accompaniment to Yorkshire pudding?", "Cook in oven or by exposure to heat", "Have a go at", "Cooked joint", "One way to cook meat" and "Honey-based drink".)