The most common and most likely answer to this crossword clue is the 8 letter word BESTOWAL
I've seen this crossword clue in The Sunday Telegraph
B
E
S
T
O
W
A
L
More clues leading to the result BESTOWAL
- Most successful pledge disposing of Bible as a gift
- Presenting act, a bird of the highest order entertains?
- Giving first love rules to go over
- Award, one held by top Sheffield Wednesday player
- Perhaps star in parliament holds a presentation
- Cream tea finally swallowed by bird for presentation
- Act of awarding first, one bagged by night bird
- Wisest of the wise perhaps receiving first of awards, in act of generosity
- Presentation of laws to be amended
- Extremely studious person bags top-class award
Buddy explains!

The straight part
We know that "act of generosity" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case act of generosity = bestowal.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.