It's my shakiness that gives you a vague clue
I believe the answer is:
misty
'gives you a vague clue' is the definition.
I can't tell whether this defines the answer.
'it's my shakiness' is the wordplay.
'it's my' anagrams to 'MISTY'.
However, I am not clear how this is indicated.
'that' acts as a link.
Can you help me to learn more?
(Other definitions for misty that I've seen before include "Cloudy, foggy" , "Dim, indistinct" , "unclear" , "Slightly fogged" , "Indistinct in outline" .)