The obvious exception being the Frostwolf & Warsong clan (Just because they have battlegrounds) & The Mag'har but they are from Outland & become part of the "new horde" after the fact.
The old horde was formed of many many clans & with Thrall wanting the orcs to "get back to their roots" why is it now a days the individual clan identities are non existent.
*Edit: & by horde I mean Thrall/Garrosh's horde. Not the Dark Horde or Fel Horde, both of which clearly identify the clans within.