Lizard George found around rock half-hidden (5)
I believe the answer is:
gecko
'lizard' is the definition.
(I know that gecko is a type of lizard)
'george found around rock half-hidden' is the wordplay.
'george' becomes 'geo'.
'found around' is an insertion indicator.
'half-hidden' means to take half the letters.
'rock' cut in half is 'ck'.
'geo' enclosing 'ck' is 'GECKO'.
(Other definitions for gecko that I've seen before include "Lizard than can't blink" , "Cold-blooded creature" , "Cold-blooded type" , "Thick-bodied lizard" , "Small tropical lizard" .)