The most common and most likely answer to this crossword clue is the 15 letter word BLACK-AND-WHITE
I've seen this crossword clue in The Times
B
L
A
C
K
-
A
N
D
-
W
H
I
T
E
More clues leading to the result BLACK-AND-WHITE
Buddy explains!
The straight part
We know that "not allowing any middle ground" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case not allowing any middle ground = black-and-white.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 BLACK-AND-WHITE mean?
BLACK-AND-WHITE adjective- Easily divided into diametrically opposing camps or schools of thought.
- Of art, a photograph or photography, using shades of grey/gray rather than colour/color.
- Of a television or monitor, displaying images in shades of grey/gray rather than colour/color.
- Classifying people, objects or concepts as two polar opposites, especially "right" and "wrong"; dichotomous and inflexible.