The most common and most likely answer to this crossword clue is the 7 letter word TEDIOUS
I've seen this crossword clue in Financial Times
T
E
D
I
O
U
S
More clues leading to the result TEDIOUS
- Running outside is boring
- Tiresome English girl captivated by all of Paris
- Tiresome foreign diet followed by ordinary American
- Dull and grey outside in a storm
- It’s not exciting messing around outside
- Flat outside is in a bad way
- Working outside can be boring
- I used to be stupid and boring
- Lunatic outside is boring
- Eccentrically suited with nothing drab
Buddy explains!
The straight part
We know that "Flat" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case flat = tedious.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 TEDIOUS mean?
TEDIOUS adjective- Boring, monotonous, time-consuming, wearisome.