The most common and most likely answer to this crossword clue is the 5 letter word GROWN
I've seen this crossword clue in The Times
G
R
O
W
N
More clues leading to the result GROWN
- Mature combination of companies adopting western name
- Having got bigger reaction to bad joke perhaps when broadcast
- Big argument? No good going back over it!
- Fully developed formal dress? About right
- Audibly, complaint increased in volume
- Queen wearing dress got larger
- Raised bank within garden’s borders
- Developed grand place for 14th in line?
- Filled out a complaint, say
- Good incentive taken up to employ individual adults
Buddy explains!

The straight part
We know that "Mature" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case mature = grown.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 GROWN mean?
GROWN verb- To become larger, to increase in magnitude.
- To appear or sprout.
- To develop, to mature.
- To cause or allow something to become bigger, especially to cultivate plants.
- To assume a condition or quality over time.
- To become attached or fixed; to adhere.
- Covered by growth; overgrown.
- Of a person: adult.