If you have the name for the unclued entry, there's a particular number associated with his work - this dictates the number of letters to change for each entry (always the same number but different letters each time - the letters are consecutive and not random... even though they might appear to be).
drxx...thanks for the useful hints on this one ....is it something to do with his Quartet? Can't see how it relates though..will leave it for a while and come back later hopefully with a fresh view!
once you see how many letters are changed each time you'll have your answer, xwordfan (and you'll be exchanging parts of a ... from one artform for parts of a ... from a different artform).
novice - look at the individual titles for the E set - and look for matching sequences of letters (matching the letters that are clashing in the answers).
Then look at the short names within the H sets that fit into the gaps.
You're replacing pieces of one group of ...s with pieces from another group of ...s
...and it's always the same small number for each change - I was tempted by a slightly longer possibility in an entry that had no clashes but that was a mistake (one of the answers to be changed is much shorter than the others, it has only 1 of its original letters left after the swap).