Glove puppet isn't under control (2,1,6)
I believe the answer is:
on a string
This clue is a double definition.
'glove puppet isn't' is the first definition.
(a glove puppet isn't on a string)
'under control' is the second definition.
(I've seen this before)
(Other definitions for on a string that I've seen before include "under complete control" , "left dangling?" , "Yo-yo is" , "under one's control" , "Pearl may be" .)