It is rare if you don't find it well done (5)
I believe the answer is:
steak
'it is rare if you don't find it well done' is the definition.
The definition suggests a singular noun which matches the answer.
This is all the clue.
Can you help me to learn more?
(Other definitions for steak that I've seen before include "Thick slice of meat" , "- - tartare" , "Fleshy piece of meat" , "pale by the sound of it" , "Getting cut" .)