The most common and most likely answer to this crossword clue is the 5 plus 5 letter word BLACK WIDOW
I've seen this crossword clue in The Guardian
B
L
A
C
K
W
I
D
O
W
More clues leading to the result BLACK WIDOW
- Spinner providing Boycott with opportunity? That’s not new
- Poisonous creature threatening woman whose husband is late
- Boycott opening, lacking new web designer
- Dark-haired woman, now alone and a bit of a maneater?
- East End houses don’t have the credentials to accommodate white 25
- Venomous American chess player opening with sacrifice of knight
Buddy explains!
The straight part
We know that "25" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case 25 = black widow.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.