Become a couch potato? (8)
I believe the answer is:
vegetate
'become' is the 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?
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for vegetate that I've seen before include "Lead a dull and inactive life" , "Do very little" , "Live a dull inactive life" , "Live uneventful life, stagnate" , "appears to be inert" .)