The most common and most likely answer to this crossword clue is the 7 letter word TRITEST
I've seen this crossword clue in The Times
T
R
I
T
E
S
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Buddy explains!
The straight part
We know that "Most banal" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case most banal = tritest.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 TRITEST mean?
TRITEST adjective- Often in reference to a word or phrase: used so many times that it is commonplace, or no longer interesting or effective; worn out, hackneyed.
- So well established as to be beyond debate: trite law.