I have a full grid, but cannot parse 1 down. I know the 10 extra letters and their 10 definitions and have the six words of the statement - although I'm not sure if these are in the right order. I have no idea of the final word, the earlier work nor the person responsible - despite painful grid staring. I do wish that the time and effort required to solve the listener was not directly proportional the difficulty of the PDM and indirectly proportional to the ease of the solve.
Gitto, 1 dn. A common contraction for against is removed from a 9 letter word for registered. def lines and 2nd word in clue to be removed. I can thoroughly recommend the work to those who don't know it. Deserving of a much wider audience.
Crucifer, did you know there was some mix-up involving the number of letters? There's more on Answerbank. I don't know if this will be of any help, but I decided to mention it anyway!
Gitto - look in usual places for person's name, with changes to leave words.
I think I have got one of the extra words (or letters?) wrong as I need to get another M to make the title to be entered, even though I've paired them all up.