How to Cover or Support a Nil in Spades

"Okay, here we have a lay out and perhaps the clubs are really immaterial, let's just suppose that you happen to have four middle clubs. The jack, ten, eight, six, the club suits not really important here. Your side has bid nil and you've bid four, now you've bid in front of your partner and you thought you'd take two diamonds and possibly two spades or maybe that was a jack, certainly you've bid three or four depending on the quality of the spades. So let's say you have the ace of clubs on the side. So you've made a comfortable bid of four; two diamonds, a spade and a club trick seem to be pretty reasonable. And low and behold this guy comes up with a five and your partner really likes that because he's got a lowest hand he got a five bid in front of him, he's got nine tricks bid in front of him. So he wanders into nil he doesn't wander into nil, your sides bidding to win the game or your sides bidding to make up points, so you feel like you've got it made. So now your partners in nil, and low and behold, you happen to, well you don't have the lead here, this guy takes the lead and he leads a club and your partner puts on a jack because maybe he came into it with a jack and now he plays small and you're forced to play. What do you do here? Your partner may have bid a bad no with the jack of clubs, but regardless you're going to start your longest suit to try to cover him. You want your partner to get discards or you want your partner to be able to get rid of bad cards in his hand. So you start out with the ace of diamonds, and this guy obviously throws a high card under it because he wants to keep some control over the nil. And your partner under that ace of diamonds throws a nine."