The most common and most likely answer to this crossword clue is the 7 letter word PREMIER
I've seen this crossword clue in The Guardian
P
R
E
M
I
E
R
More clues leading to the result PREMIER
- Film director with no good cut is top in Rank
- Top-notch rock band in seaside attraction
- Voyeur embracing this setter over cardinal
- . Prime minister of empire- building Queen?
- First rock band introduced to a member of the nobility reportedly
- Do successors occupy country, having ousted last PM?
- Earliest PM
- Totally clean? Not you, no way, Mr Johnson
- Top music group given external support
- Leading politician has popular group in support
Buddy explains!

The straight part
We know that "Johnson" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case johnson = premier.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 PREMIER mean?
PREMIER noun- (Westminster system) The head of government in parliament and leader of the cabinet.
- (non-Westminster) The government leader in a legislative congress or leader of a government-level administrative body; the head of government.
- The first lieutenant or other second-in-command officer of a ship.
- (sporting) The champion team of a particular season (especially as used in Australian rules football).
- To perform, display or exhibit for the first time.
- To govern in the role of premier.
- Foremost; first or highest in quality or degree.
- Most ancient.