It makes clothes hard to wear (6)
I believe the answer is:
starch
This clue could be a double definition.
'it makes clothes hard' is the first definition.
The definition suggests a singular noun which matches the answer.
'wear' is the second definition.
The answer and definition can be both related to change as well as being verbs in their base form.
Perhaps they are linked in a way I don't understand?
'to' acts as a link.
Can you help me to learn more?
(Other definitions for starch that I've seen before include "rigid" , "Stiffener in the laundry" , "Carbohydrate; stiffen" , "It stiffens shirts and collars" , "Stiffness of manner" .)