I don't believe Clune will be back as a player. Maybe a member of the training or coaching staff sure, but it is going to be hard enough for Greening to get playing time next year at wing, much less Clune.
It is not exactly the best place to discuss this, but Greening played almost every game he could (I think he missed 3 games all year between the regular season and playoffs) and should become the captain. He may be more of a center next year, but he's getting more ice time than most.
Clune already in kind of a player-coach role, and I think he will continue to be that. He slots into games where we need toughness, or slots into a fair number of games when a defensive forward needs a rest. He's not old and while he did not put up a ton of points, he still played well in 47 games for the Marlies last year. I can't think of a better enforcer type to replace him right now.