G, you may very well have got there by now, but here's another hint. The three unclued down entries are all types of the unclued across entry, as I imagine you've deduced. You've found one relevant word in the top row and, if you look it up in Chambers, you'll see that it mentions a connection with one of the three types. In row 2 you'll find a similar word and a similar connection with one of the remaining two types.
I myself just can't be bothered doing the word-search, so I haven't done the drawing, but I imagine - though I may be desperately wrong - the illustration will probably look like the THIRD type so far undealt with. See it by googling.
Good luck. In fact - if you do finish - come back and tell me all about it! (I won't be submitting.)