The most common and most likely answer to this crossword clue is the 9 plus 5 letter word PRACTICAL JOKER
I've seen this crossword clue in The Times
P
R
A
C
T
I
C
A
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J
O
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R
More clues leading to the result PRACTICAL JOKER
Buddy explains!
The straight part
We know that "tricks are what I do" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case tricks are what i do = practical joker.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.