The most common and most likely answer to this crossword clue is the 4 letter word OURS
I've seen this crossword clue in The Daily Telegraph
O
U
R
S
More clues leading to the result OURS
- Some time, so to speak, for you and me
- For you and me, time’s called
- Top squares belonging to Guardian supporters
- What we have is time, we hear
- It’s yours and mine, of course
- Time without potential for aspiration? That belongs to us.
- Sounds just a matter of time for us
- For you and me, time's called
- British heading off on hols
- Time, they say, is what we have
Buddy explains!

The straight part
We know that "It’s yours and mine" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case it’s yours and mine = ours.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 OURS mean?
OURS pronoun- That which belongs to us; the possessive case of we, used without a following noun.