The most common and most likely answer to this crossword clue is the 5 letter word ALPHA
I've seen this crossword clue in Independent
A
L
P
H
A
More clues leading to the result ALPHA
- Triumphant cry on clinching record, that’s followed by “Bravo”
- Greek character in hotel in mountain area
- Greek character has not finished passing mountain
- Expression of surprise about recording getting top position?
- Mark of excellence in trial phase
- A top mark
- For Greeks, a sacred river first of all
- I'm surprised to secure record top mark
- A Greek last seen in Sparta?
- Top record-holding Norwegian band
Buddy explains!

The straight part
We know that "A" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case a = alpha.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 ALPHA mean?
ALPHA noun- The name of the first letter of the Greek alphabet (Α, α), followed by beta. In the Latin alphabet it is the predecessor to A.
- Latin alpha
- The name of the symbols Α and α used in science and mathematics, often interchangeable with the symbols when used as a prefix.
- The return of a given asset or portfolio adjusted for systematic risk.
- A person, especially a male, who is dominant, successful and attractive; (see alpha male).
- (abbreviation) Alphabet.
- The first versions of a program, usually only available to the developer, and only tested by the developer.
- The level of translucency of a color, as determined by the alpha channel.
- The significance level of a statistical test; the alpha level.
- In omegaverse fiction, a person of a sexually-dominant (and sometimes secondary) gender/sex that is driven by biology, magic, or other means to bond with an omega, with males of this type often having canine-like genitalia.
- Designates the first in an order of precedence.
- (of person, object or action) exhibiting characteristics of the alpha male/female archetype.
- Designates some bright star, usually the brightest star, of a constellation.