After my turns, knee's beginning to wobble (4)
I believe the answer is:
rock
'wobble' is the definition.
(thesaurus)
'after my turns knee's beginning' is the wordplay.
'after' is a charade indicator (letters next to each other).
'my' becomes 'cor' (I've seen this in other clues**).
'turns' is a reversal indicator.
'beginning' indicates taking the first letters.
The first letter of 'knee' is 'k'.
'cor' backwards is 'roc'.
'roc' put next to 'k' is 'ROCK'.
'to' acts as a link.
(Other definitions for rock that I've seen before include "Sway to and fro - mass of stone" , "Seaside confectionery" , "Hard stone or lively music" , "Be unstable; lull (baby)" , "Sway - very big stone" .)