FOX News is reporting that the FBI has been questioning Clinton's IT dude in such a way as to try to tie together images of then-Secretary Clinton using her electronic devices with the email server's records. The claim is that they are trying to put together voids in the email record, so they can get some sense of just what she deleted as "personal" and never turned over to State.
They are, in other words, looking at her personally. They want to know exactly what she herself was doing, and how it ties into the records they are examining.
If that's not a "target" of the investigation, it's certainly a "subject" of the investigation in the technical terminology they use. The real point of her denials of being a "target" is that she wants to say something like this:
This is just a security review! Nobody is thinking of indicting me!
If they're looking at images of her and trying to tie them to events, though, they're looking at her personally. This was never just a security review, but it might have been targeted at finding a scapegoat among her chief aides. Now it sounds like they are doing the right thing, and targeting her personally for her manifest and constant violations of national security law.