Mine entrance required: reportedly do this, then? (4)
I believe the answer is:
adit
This might be a double definition.
'mine entrance' is the first definition.
(I've seen this before)
'reportedly do this then?' is the second definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'required' is the link.
(Other definitions for adit that I've seen before include "Da, it is a mine entrance" , "Horizontal mine drainage shaft" , "Horizontal mine passage" , "Passageway into a mine" , "Means of access to mine" .)