Shaky bit of singing (5)
I believe the answer is:
trill
'shaky bit' is the definition.
'trill' can be an answer for 'bit' (I have seen 'bit of birdsong' mean 'trill' so perhaps 'bit' could also mean 'trill'). I'm not certain of the 'shaky' bit.
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for trill that I've seen before include "Shrill warble" , "High-pitched warbling sound" , "Rapid alternation of notes" , "bit of birdsong" , "Quavering note" .)