The most common and most likely answer to this crossword clue is the 4 plus 2 plus 9 letter word FULL OF SURPRISES
F
U
L
L
O
F
S
U
R
P
R
I
S
E
S
Buddy explains!
The straight part
We know that "Tricky to anticipate" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case tricky to anticipate = full of surprises.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.