The most common and most likely answer to this crossword clue is the 5 letter word BLAND
I've seen this crossword clue in The Guardian
B
L
A
N
D
More clues leading to the result BLAND
- British state is rather dull and uninteresting
- Belgium win – boring
- Dull Black Country character of 1 12
- Dull lecturer accepted by group
- Flat British countryside
- Smooth learner in orchestra
- Gentle British countryside
- Black Country is dull
- Black Country not particularly interesting?
- Gentle Bob Dylan playing 'lost boy'
Buddy explains!

The straight part
We know that "Dull/character of 1 12" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case dull/character of 1 12 = bland.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 BLAND mean?
BLAND adjective- Having a soothing effect; not irritating or stimulating.
- Lacking in taste, flavor, or vigor.
- Lacking interest; boring; dull.
- Mild; soft, gentle, balmy; smooth in manner; suave.
- To mix; blend; mingle.
- To connect; associate.
- Mixture; union.
- A summer beverage prepared from the whey of churned milk, common among the inhabitants of the Shetland Islands.