Where the millenium-minded could pass a bit of time (4)
I believe the answer is:
dome
'where the millenium-minded' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'pass a bit of time' is the wordplay.
'pass' becomes 'do' (doing is a kind of passing).
'a bit of time' becomes 'me' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'do'+'me'='DOME'
'could' acts as a link.
Can you help me to learn more?
(Other definitions for dome that I've seen before include "Rounded vault of a roof" , "Old cathedral" , "Curved roof" , "Rounded roof with circular base" , "Cupola - millennium building" .)