The most common and most likely answer to this crossword clue is the 9 letter word TREMBLIER
I've seen this crossword clue in Independent
T
R
E
M
B
L
I
E
R
Buddy explains!
The straight part
We know that "Shakier" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case shakier = tremblier.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 TREMBLIER mean?
TREMBLIER adjective- In a trembling or shaking state