A quick rinse-down for you who got stuck:
ACROSS
2A. anag. LAP + ultimately "has" = S. 4A. In Spain, "the" = EL + blade = FIN. 7A. Reversal of friend = PAL. 8A. Way of working (modus operandi) = MO + Seine = NET. 9A. Lead to silver = S + sticky stuff = TAR.
DOWN
1D. double def. 2D. homophone of "a good deal" = "A LOT". 3D. Circular figure = PI + for every = PER. 5D. strong = F + removal of depth (= d) from "and". 6D. double def.