The most common and most likely answer to this crossword clue is the 13 letter word HOBSON-JOBSON
H
O
B
S
O
N
-
J
O
B
S
O
N
Buddy explains!
The straight part
We know that "festival excitement" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case festival excitement = hobson-jobson.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.