warhorse

Short definition from Wiktionary

Noun

1. 1
   Any horse used in horse-cavalry, but especially one bearing an armoured knight.
2. 2
   An experienced person who has been through many battles, situations or contests; someone who has given long service.
3. 3
   A regularly revived theatrical or musical work, as with Hamlet or a Beethoven symphony, or as excerpts thereto. May imply that the work in question has become hackneyed.