Eggsandbacon...but Chambers doesn't seem to have it. Personally, I just wrote it in on the basis that I had from cross-letters...EG?S??DB?CON. The clue elements are satisfied...eggs = spurs (as in spurs on)...and = with...defender is back and on = entertaining (as in onstage). The 'k' is removed because of 'king absent'. I've never heard of the word.
I should have pointed out above that 'eggs and bacon' is listed in The Oxford English Dictionary as a plant-name, so hence I suppose the clue's reference to 'clover'.