Drug used by journalist - one about to enter pit (8)
I believe the answer is:
medicine
'drug' is the definition.
(medicine is a kind of drug)
'journalist one about to enter pit' is the wordplay.
'journalist' becomes 'ed' (short for editor).
'one about to' becomes 'ic' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'enter' means one lot of letters goes inside another.
'pit' becomes 'mine' (mining pit).
'ed'+'ic'='edic'
'edic' going inside 'mine' is 'MEDICINE'.
'used by' acts as a link.
Can you help me to learn more?
(Other definitions for medicine that I've seen before include "doctor" , "It's used to treat disorders and diseases" , "It's taken to treat disease" , "The practice of diagnosis and treatment of disease" , "Remedial punishment" .)