The most common and most likely answer to this crossword clue is the 6 plus 2 plus 3 letter word BUNDLE OF FUN
I've seen this crossword clue in The Times
B
U
N
D
L
E
O
F
F
U
N
Buddy explains!
The straight part
We know that "a jolly figure" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case a jolly figure = bundle of fun.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.