Transform sauce, perhaps, with kitchen blender (7)
I believe the answer is:
thicken
'transform' is the definition.
The answer and definition can be both related to change as well as being verbs in their base form.
Maybe you can see an association between them that I can't see?
'sauce perhaps with kitchen blender' is the wordplay.
'kitchen' can be anagrammed to 'THICKEN'.
However, I'm not clear how this is indicated.
Can you help me to learn more?
(Other definitions for thicken that I've seen before include "Become more viscous" , "Become more dense (as plots do)" , "Become more involved" , "Make dense" , "Clot" .)