Tear all to pieces sideways (7)
I believe the answer is:
lateral
'sideways' is the definition.
(I've seen this before)
'tear all to pieces' is the wordplay.
'to pieces' indicates an anagram (the same pieces in a new order).
'tear'+'all'='tearall'
'tearall' anagrammed gives 'LATERAL'.
(Other definitions for lateral that I've seen before include "This kind of sideways thinking does not use conventional logic" , "to one side" , "Side branch" , "Edgeways" , "Possibly right" .)