Seesaw transformed local site (9)
I believe the answer is:
oscillate
'seesaw' is the definition.
(I've seen this before)
'transformed local site' is the wordplay.
'transformed' indicates an anagram.
'local'+'site'='localsite'
'localsite' with letters rearranged gives 'OSCILLATE'.
(Other definitions for oscillate that I've seen before include "seesaw" , "Swing like a pendulum" , "Move to and fro like a pendulum" , "Rock" , "Swing back and forth" .)