It is clever. They are known as “lift and separate” clues, where a phrase in common parlance has to be split up in order to make sense of the clue. This is the history, with a few examples:
All of the extra letters from down clues are used in the instruction (there is no extra letter in the anagram clue, of course). If you say which clues you think have redundant extra letters, we may be able to clarify.