This isn't an accipiter of any kind.
When you look at a raptor (or any bird for that matter), your first step should be to look at the shape and size. Although they're cut off in the photo, this bird will have a medium length tail and medium-length, very pointed wings, and has a very sleek, compact appearance overall. Accipiters (Sharp-shinned, Cooper's and Goshawk) have long tails and short, fairly rounded wings, giving a very different appearance.
The shape should point you towards the falcons, and there are numerous plumage features which then make it clear this is a Merlin.
The shape differences may seem subtle at first, but with a little experience they are quite obvious and these differences make raptors much easier to identify.
