According to reports in the Telegraph and the Independent, Arsene Wenger is still looking to add to Arsenal's first-team squad for the new season. The emphasis is on a defender, although as has been reported in the past, a midfielder with the versatility to also play in the back would also be a favored possibility.
Both papers name the same trio of prospective signings. We've been talking about William Carvalho for quite a while, and once again, here he is. Luis Gustavo is a familiar name from last summer, and while he ended up leaving Bayern Munich for Wolfsburg rather than Arsenal, he offers much the same positional skillset as Carvalho - primarily a midfielder, but can also play in central defense. Benedikt Höwedes of Schalke 04 is a defender exclusively, though as World Cup watchers will know, he can play as a fullback in addition to his favored position in the middle of the defense.
If I had my pick, I'd still probably choose Carvalho, and I'd prefer to have a midfielder who can cover in the back line than a dedicated defender. But one way or the other, I think Arsenal are still a signing away from being able to maintain a full-season challenge on the three primary fronts. One of these three would do.