Coach penning collection of books, wanting iodine for blisters (7)
I believe the answer is:
bubbles
'blisters' is the definition.
The definition and answer can be both related to change as well as being verbs in their -s form.
Perhaps there's an association between them I don't understand?
'coach penning collection of books wanting iodine' is the wordplay.
I cannot quite see how this works, but
'books' could be 'bb' (two abbreviations for book) and 'bb' is found within the answer.
This explanation may well be incorrect...
'for' acts as a link.
Can you help me to learn more?
(Other definitions for bubbles that I've seen before include "Painting" , "Fizzes" , "is very vivacious" , "Michael Jackson's monkey" , "Little balls of soap and water" .)