An easy subject? (6)
I believe the answer is:
sitter
'an easy subject?' is the definition.
The answer and definition can be both people as well as being singular nouns.
Perhaps there's an association between them I don't understand?
This is the entire clue.
Can you help me to learn more?
(Other definitions for sitter that I've seen before include "One posing for artist" , "A poser" , "Child-minder of sedentary disposition" , "broody type" , "Artist's model or child's minder" .)