The most common and most likely answer to this crossword clue is the 5 plus 7 letter word THREE SISTERS
I've seen this crossword clue in The Guardian
T
H
R
E
E
S
I
S
T
E
R
S
More clues leading to the result THREE SISTERS
Buddy explains!
The straight part
We know that "play" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case play = three sisters.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.