The most common and most likely answer to this crossword clue is the 5 letter word LINED
I've seen this crossword clue in The Guardian
L
I
N
E
D
More clues leading to the result LINED
- Covered on the inside with wrinkles
- Some drivel in edition with ruling
- A warm jacket may be so worn
- Family with daughter showing signs of age?
- Scored, though visibly ageing?
- Score on date, with internal covering
- How paper might be in possession of pupil, ineducable
- Insulated home protected by electronic device
- Curtains may be so connected with no end of work
- Gave false report about North having rules
Buddy explains!

The straight part
We know that "showing signs of age" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case showing signs of age = lined.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 LINED mean?
LINED verb- To place (objects) into a line (usually used with "up"); to form into a line; to align.
- To place persons or things along the side of for security or defense; to strengthen by adding; to fortify.
- To form a line along.
- To mark with a line or lines, to cover with lines.
- To represent by lines; to delineate; to portray.
- To read or repeat line by line.
- To hit a line drive; to hit a line drive which is caught for an out. Compare fly and ground.
- To track (wild bees) to their nest by following their line of flight.
- To measure.
- To cover the inner surface of (something), originally especially with linen.
- To reinforce (the back of a book) with glue and glued scrap material such as fabric or paper.
- To fill or supply (something), as a purse with money.
- (of a dog) To copulate with, to impregnate.
- Having a lining, an inner layer or covering.
- (of paper) Having lines, ruled.
- (of skin) Having visible lines or wrinkles.