Monitor cooked her toast (8)
I believe the answer is:
rheostat
'monitor' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'cooked her toast' is the wordplay.
'cooked' is an anagram indicator (letters cooked into a new form).
'her'+'toast'='hertoast'
'hertoast' is an anagram of 'RHEOSTAT'.
Can you help me to learn more?
(Other definitions for rheostat that I've seen before include "Current controller" , "The rotas (anag.)" , "The roast (anag.); electrical instrument" , "Current regulator" , "Means of controlling resistance" .)