The most common and most likely answer to this crossword clue is the 7 letter word SUPREME
I've seen this crossword clue in The Guardian
S
U
P
R
E
M
E
More clues leading to the result SUPREME
- Presume needs fixing, above all
- Mary Wilson perhaps unsurpassed
- Greatest power invested in certain author
- Foremost Irish girl gets discharge, when rejected
- Presume dancing is best
- Excellent drink taken with army engineers
- Very powerful backing for soul singer
- Drink most of wine with yours truly and Diana Ross?
- Crowning the young Diana R.?
- Presume wrongly to be the greatest
Buddy explains!

The straight part
We know that "Foremost" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case foremost = supreme.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.
What does SUPREME mean?
SUPREME noun- The highest point.
- A pizza having a large number of the most common toppings, such as pepperoni, bell peppers, onions, mushrooms, olives, etc.
- A breast of chicken or duck with the wing bone attached.
- Anything from which all skin, bones, and other parts which are not eaten have been removed, such as a skinless fish fillet.
- To divide a citrus fruit into its segments, removing the skin, pith, membranes, and seeds.
- Dominant, having power over all others.
- (sometimes postpositive) Greatest, most excellent, extreme, most superior, highest, or utmost.
- Situated at the highest part or point.