Double Entendre by Ximenes

 Dedicated to Afrit, pioneer and consultant.   1 ac. has a normal clue: the rest of the clues may each be read so as to  lead to two separate  answers by means of definition (always) plus (in most cases but not all) a secondary clue of one or the usual types. The whole of each of these clues, without any omission, is to be taken as a complete clue to each of its two answers: the solver must discover into which of the two   available numbered spaces each answer fits. 

ACROSS — 1. Being able to bat in two ways, I've got our bats mixed, very mixed (12) 6. Fair one in myth, a bit of a worm, is old enough to spell her name another way (6, 6) 7. One's ration here is a jumble; it requires someone (usually female with broom) to clear out (6, 6) 8. Anciently named land to West, later taking Rum, for instance, in the inner parts — I'm   English first and last, my heart a match for Pest (6, 6) 10. For a token of recognition, see me, head and foot, wrong way round: put in what may be   the first thing you associate with blindness (6, 6) 12. The solver should weigh in with an English river about: he'll then complete the answer — it's to be cross (6, 6) 16 Can you find something yellowish? Must give it a try, or fail (6, 6) 17. There's room for food here: if you make a god of it, you won't leave any in sight, which is vulgar (6, 6) 18. No work — money short — not a penny in extremity — can't even see the pictures — still life may go on (6, 6) 19. I have to see about the very latest thing; my correspondents put my name on their despatches (6, 6)

DOWN — 1. Mix up, imperfectly seen, gives you clue for solution (7, 7)  2. Only once let there be a bust up, and a bust up may make me blood-stained (5, 5) 3. You've come to rob doily, perhaps: then I, very thoughtfully, like a dicky b-burrdee, will alter it (8, 8) 4. There's a shortage to be found, for instance, in unloadin' Glenlivet: that means a hollow space (6, 6)  5. What comes out of trees? Animal fat, perhaps (5, 5) 9. Not being content with the same old dull routine, change a popular insect -- put it in! (8, 8)  11. Plunge into the meer river or loch, so as to get a farmer, yielding half his substance, involved in the produce of seed (7, 7) 13. An infernal Greek goddess shattered and aged that the stock may well get outside (6, 6) 14.  Birds hiding in a Toledo vestry, perhaps (5, 5) 15. Provide a fount of grace for a Roman Catholic in decline (5, 5)