What beasts have done time ... here? (7)
I believe the answer is:
dungeon
'what beasts have done time here?' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'time here?' is the wordplay.
I cannot really understand how this works, but
'time' could be 'eon' (eon is a kind of time) and 'eon' is present in the answer.
The remaining letters 'dung' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for dungeon that I've seen before include "Underground prison-cell" , "Uncongenial accommodation" , "Eg, the Black Hole of Calcutta" , "old prison" , "prison the result" .)