The most common and most likely answer to this crossword clue is the 4 letter word OLD*
I've seen this crossword clue in The Guardian
O
L
D
*
Buddy explains!

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 OLD* mean?
OLD* noun- (with the, invariable plural only) People who are old; old beings; the older generation, taken as a group.
- (in combination) One of a specified age.
- A person older than oneself, especially an adult in relation to a teenager.
- (most often plural) One's parents.
- Of an object, concept, relationship, etc., having existed for a relatively long period of time.
- Having been used and thus no longer new or unused.
- Having existed or lived for the specified time.
- (heading) Of an earlier time.
- Tiresome after prolonged repetition.
- Said of subdued colors, particularly reds, pinks and oranges, as if they had faded over time.
- A grammatical intensifier, often used in describing something positive. (Mostly in idioms like good old, big old and little old, any old and some old.)
- Excessive, abundant.