Shake the stone it is hiding inside (7)
I believe the answer is:
agitate
'shake' is the definition.
(I know that shake can be written as agitate)
'stone it is hiding inside' is the wordplay.
'stone' becomes 'agate' (I've seen this before).
'it is hiding' indicates putting letters inside.
'inside' becomes 'it' (I can't explain this - if you can you should believe this answer much more).
'agate' going around 'it' is 'AGITATE'.
'the' acts as a link.
Can you help me to learn more?
(Other definitions for agitate that I've seen before include "'Stir, excite (7)'" , "Upset, stir" , "Perturb" , "Disturb or shake" , "Stir (up public opinion?)" .)