Pass round a dirty place, a Government building (7)
I believe the answer is:
capitol
'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).
'a'+'pit'='apit'
'col' placed around 'apit' is 'CAPITOL'.
Can you help me to learn more?
(Other definitions for capitol that I've seen before include "Seat of US Congress" , "American Congress building" , "US Senate and House of Representatives building" , "US Congress building" , "Roman temple" .)