Thanks unclued - it's easily done ;-)
The problem I have with this one is that we traditionally understand 'clashes' to refer to single letters unless otherwise specified. Usually puzzles in the past that have used this device to present extra thematic information make it much clearer that the gaps created in words by the removal of letters vary in length. Identifying grid entry lengths and therefore the location of the clashes in this puzzle was relatively easy once the indexation was solved, but with such an obscure quotation this was no mean feat when most of the clues have to be solved independently. In short, I suppose I don't like my puzzlement to feel like punishment (unless it's a Schadenfreude of course ! )