Is ONE PIECE episode 393 filler?
Canon No, episode 393 of ONE PIECE is canon.
#393
The Target is Camie! The Looming Clutches of a Professional Kidnapper
標的はケイミー!!迫る人攫い屋の魔手
Aired 15 Mar 2009
Mochibayo compiled this list from MyAnimeList's labels, because MyAnimeList's episode data is not reaching us at the moment.