The most common and most likely answer to this crossword clue is the 5 letter word REVEL
I've seen this crossword clue in Financial Times
R
E
V
E
L
More clues leading to the result REVEL
Buddy explains!

The straight part
We know that "Celebrate" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case celebrate = revel.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 REVEL mean?
REVEL noun- An instance of merrymaking; a celebration.
- A kind of dance.
- A wake for the dead.
- To make merry; to have a happy, lively time.
- To take delight (in something).
- The outer side of a window or door frame; the jamb.
- A revelation; an uncovering of what was hidden.
- (obsolete in the US) The side of an opening for a window, doorway, or the like, between the door frame or window frame and the outer surface of the wall; or, where the opening is not filled with a door, etc., the whole thickness of the wall; the jamb.
- To draw back; to retract.