The most common and most likely answer to this crossword clue is the 10 letter word GLADDENING
I've seen this crossword clue in Independent
G
L
A
D
D
E
N
I
N
G
Buddy explains!

The straight part
We know that "pleasing" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case pleasing = gladdening.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 GLADDENING mean?
GLADDENING verb- To cause (something) to become more glad.
- To become more glad in one's disposition.