Turner that can be viewed from both sides (5)
I believe the answer is:
rotor
I believe this clue is a double definition.
'turner' is the first definition.
(something that turns)
'that can be viewed from both sides' is the second definition.
(Other definitions for rotor that I've seen before include "Turner" , "I go round" , "It lifts helicopter" , "Spinner" , "US state South of L. Erie" .)