The most common and most likely answer to this crossword clue is the 5 letter word AGING
I've seen this crossword clue in The Daily Telegraph
A
G
I
N
G
More clues leading to the result AGING
- 7 Carrying on dismissing leader no longer up-to-the-minute?
- Maturing alcohol in silver
- A spirit good for maturing
- Getting on a horse outside pub, say
- Maturing drink in silver container
- In decline, top lawyer drinks strong liquor
- Maturing drink in silver case
- Growing old? Getting angry! Not right
- Furious — Red leader isn’t showing sign of growing mature
Buddy explains!

The straight part
We know that "Maturing" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case maturing = aging.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 AGING mean?
AGING verb- To cause to grow old; to impart the characteristics of age to.
- To postpone an action that would extinguish something, as a debt.
- To categorize by age.
- To grow aged; to become old; to show marks of age.
- The process of becoming older or more mature.
- The deliberate process of making something (such as an antique) appear (or, in science fiction, become) older than it is.
- Becoming senescent; accumulating damage to macromolecules, cells, tissues and organs with the passage of time; progressing loss of health, mobility, vibrancy and body functionality, resulting in biological death.
- Wear, wear and tear.
- Becoming elderly.