Needed the 2nd nudge to keep me from trying to utilize the two long multi-word down entries 3D3DExtreme unction[---------] and 32D32DReduce the nominal value of stock or goods[---------] (since I expected a longer phrase that four letters).
I expected that the last word of the phrase was key, but needed the 3rd nudge to add the missing link my (after which I knew the rest of the mechanism) - but I still needed to google to identify the cultural references for the last second and third themers, and then backsolved to prove the last letter. So no way this one was going to come to fruition without much help. Good effort on your part, though.