Are ice-picks used to work in it? (7,4)

I believe the answer is:
diamond mine
'are ice-picks used to work' is the definition.
I don't know anything about this answer so I can't tell whether it can be defined by this definition.
'in it?' is the wordplay.
I cannot really understand how this works, but
'in' is present in the answer.
'it?' could be 'e' ('e' can mean 'electronic' which is similar to 'IT') and 'e' is found within the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Another definition for diamond mine that I've seen is " source of riches?".)
