The most common and most likely answer to this crossword clue is the 7 plus 6 letter word DOWNING STREET
I've seen this crossword clue in Financial Times
D
O
W
N
I
N
G
S
T
R
E
E
T
More clues leading to the result DOWNING STREET
- Duke having setter, strangely, in place of PM
- Doctor to ring West End London location
- Trendiest gown tailored for important address
- Where ministers often go drinking with cryptic setter
- Drinking quickly, setter unsteady somewhere in London
- Doctor to ring West End tourist attraction
- Get two dinners delivered in London SW1
- Drinking on the way home? Yes, if May
- British Government out of order, setting out to repress religious education
- Where some top people reside, deserting town for resort
Buddy explains!
The straight part
We know that "in London SW1" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case in london sw1 = downing street.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.