The most common and most likely answer to this crossword clue is the 10 letter word PLEASANTRY
I've seen this crossword clue in The Daily Telegraph
P
L
E
A
S
A
N
T
R
Y
More clues leading to the result PLEASANTRY
- Storing various ales in larder is some kind of joke
- Witty style in a new essay following requests
- Criticise attempt to secure tricky sale making amusing remark?
- Friendly remark of Liberal visiting simple country folk
- Land worker, about fifty, by railway making remark
- Sally‘s in class, penning Latin
- Polite remark from bottom class choking lecturer
- Jocularity of agricultural working class, welcoming introduction from landowner
- Fields infiltrating storeroom in jest
- Agreeable comment from Left swallowed by poor workers
Buddy explains!

The straight part
We know that "fatuous remark" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case fatuous remark = pleasantry.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 PLEASANTRY mean?
PLEASANTRY noun- A casual, courteous remark.
- A playful remark; a jest.
- Anything that promotes pleasure or merriment.