Pass round a dirty place, a Government building (7)
I believe the answer is:
'a government building' is the definition.
(I've seen this before)
'pass round a dirty place' is the wordplay.
'pass' becomes 'col' (col is a term for a mountain pass).
'round' means one lot of letters goes inside another.
'dirty place' becomes 'pit' (I can't justify this - if you can you should believe this answer much more).
'col' placed around 'apit' is 'CAPITOL'.
Can you help me to learn more?
(Other definitions for capitol that I've seen before include "Home of the US Congress", "Seat of US Congress", "Washington building where USA Congress meets", "government building", "Roman temple".)