The most common and most likely answer to this crossword clue is the 1 plus 3 plus 4 letter word A BIT MUCH
I've seen this crossword clue in The Times
A
B
I
T
M
U
C
H
More clues leading to the result A BIT MUCH
- Unreasonable custom husband omitted a lot
- Contradiction in terms that's unacceptable
- Sailor gets with it, drunken chum, rather unreasonable
- One being spiteful about letter going too far
- Catching chum? Bait is unnecessary
- OTT addiction not initially associated with rejected heroin
- M is unreasonable
- A little and often becomes unacceptable
- Not on time, Greek character in cab, I suspect, beginning to hurry
- Somewhat OTT adult sank teeth into chum wickedly!
Buddy explains!
The straight part
We know that "rather unreasonable" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case rather unreasonable = a bit much.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.