Temperature, along with skin blemish, remains (5)
I believe the answer is:
trash
'skin blemish remains' is the definition.
The answer and definition can be both substances as well as being singular nouns.
Perhaps you can see an association between them that I don't see?
'temperature along' is the wordplay.
'temperature' becomes 't' (abbreviation).
'along' becomes 'rash' (I am not sure about this - if you are sure you should believe this answer much more).
't'+'rash'='TRASH'
'with' is the link.
Can you help me to learn more?
(Other definitions for trash that I've seen before include "Rubbish - destroy" , "pulp" , "Worthless items" , "Dismiss as valueless" , "Worthless people; destroy (US slang)" .)