The most common and most likely answer to this crossword clue is the 7 letter word POTOMAC
I've seen this crossword clue in The Times
P
O
T
O
M
A
C
More clues leading to the result POTOMAC
- River, river to ebbing river
- European river leads to another river, northwards, and another river
- Feature of Washington: obnoxious Trump’s overbearing manner starts to be restrained by political support group
- River to computer is a different one
- American banker in vessel with old raincoat on
- River, pool, and old coat
- Retired rozzer confiscates weapon, hawk having gone for US banker
- One river or another going South in direction of another going North
- Old Scotsman’s floored by drug runner in Washington
- US runner returned old cap and waterproof
Buddy explains!
The straight part
We know that "US runner" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case us runner = potomac.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.