The most common and most likely answer to this crossword clue is the 12 letter word OPEN-HEARTED
I've seen this crossword clue in Independent
O
P
E
N
-
H
E
A
R
T
E
D
Buddy explains!

The straight part
We know that "Generous" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case generous = open-hearted.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 OPEN-HEARTED mean?
OPEN-HEARTED adjective- Frank and candidly straightforward
- Generous and kind
- Emotionally receptive