Hack in prison, put with drug dealer (3-6)
I believe the answer is:
pen-pusher
'hack' is the definition.
Both the answer and definition are singular nouns.
Perhaps you can see an association between them that I don't see?
'prison put with drug dealer' is the wordplay.
'prison' becomes 'pen' (both can mean an enclosure).
'put with' says to put letters next to each other.
'drug dealer' becomes 'pusher' (someone who sells or pushes drugs).
'pen'+'pusher'='PEN-PUSHER'
'in' is the link.
Can you help me to learn more?
(Another definition for pen-pusher that I've seen is " Clerical worker with a boring job".)