To warm up yesterday's food can make her scoff! (6)
I believe the answer is:
reheat
'to warm up' is the definition.
(I've seen this in another clue)
'make her scoff' is the wordplay.
'make' indicates an anagram.
'scoff' becomes 'eat' (to scoff something is to eat it quickly).
'her' anagrammed gives 'reh'.
'reh'+'eat'='REHEAT'
'yesterday's food can' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for reheat that I've seen before include "Cook again" , "Of cooked food, give another go in the microwave" , "Jet engine afterburner" , "Process increasing jet engine thrust" , "Method of getting extra power from jet engine" .)