The most common and most likely answer to this crossword clue is the 7 letter word CAPITOL
I've seen this crossword clue in The Daily Telegraph
C
A
P
I
T
O
L
More clues leading to the result CAPITOL
- Pass round a dirty place, a Government building
- Where federal laws created a hidden problem in Colorado
- Defile entered by a cavity, one of 9 in Rome
- Working coal pit, state-owned establishment
- Pass round an enclosure for animal fights in temple
- Limit put on Italiangovernment building
- Government building needs pass — a very dirty place inside
Buddy explains!

The straight part
We know that "Government building" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case government building = capitol.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.