Quantities of painkillers (7)
I believe the answer is:
numbers
This clue might be a double definition.
'quantities' is the first definition.
(number is a kind of quantity)
'painkillers' is the second definition.
The definition and answer can be both man-made objects as well as being plural nouns.
Perhaps there's an association between them I don't understand?
'of' is the link.
Can you help me to learn more?
(Other definitions for numbers that I've seen before include "They subdue the pain" , "Quantities; Old Testament book" , "anaesthetists?" , "Integers" , "Biblical book - anaesthetics" .)