Group pursuing diamonds - that should cool them down (3,4)
I believe the answer is:
ice pack
'group pursuing diamonds that should cool them down' is the definition.
The definition and answer can be both substances as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'group pursuing diamonds' is the wordplay.
'group' becomes 'pack' (I am not sure about this - if you are sure you should believe this answer much more).
'pursuing' is a charade indicator (letters next to each other).
'diamonds' becomes 'ice' (slang term for diamonds).
'pack' after 'ice' is 'ICE-PACK'.
Can you help me to learn more?
(Other definitions for ice pack that I've seen before include "may be of use for a flush" , "number of arctic wolves?" , "It's used to reduce swellings and temperatures" , "Cold item held against a swollen body part" , "Cooling application" .)