noun a work of art (composition or drama) that is part of the standard repertory but has become hackneyed from much repetition.
noun an experienced person who has been through many battles.
— synonyms: veteran, old-timer, oldtimer, old_hand, old_stager, stager
noun horse used in war.
Examples
“2006 Most important though is the fact that, for the first time in I can barely remember how long, the ROH mounts a new production of an Italian repertory warhorse that is fully on the level of the one it replaces [and indeed, in some respects, surpasses it] [...] we actually have a "Tosca". — Google group.”
“"Srinath: India's warhorse" (headline from BBC News)”