Ilippu
One of the earlier across clues has no defintion. Two of the items occur in the across clues, two in the down. Probably the most unexpected item is the first and longer of the down ones.
Anagram of 1st word minus the letter indicated, followed by a 2 letter word for "space" in the typographical sense. Insert two instances of the letter you have identified, definition is last word.
That came together very nicely. The title of the work yielded quite early on for me. Works containing lists of items are useful thematic devices it seems… not so long since we had the Jumblies with their collection of things.
Can anyone help with 19a? I can't believe I've got the down clues wrong. But my answers for 17d and 20d seem to rule out any possible answer for 19a, even when I try inserting a blank in different places. Do the first two words of 17d correspond to a 3-letter surname that I've googled? And is the 4th word in 20d represented by one letter? If I'm right, I'm baffled as to what 19a could be. 15d and 9d can't possibly be wrong and I can't have entered them wrong - the crossers confirm. But am stuck stuck stuck on 19a.