It's very easy to be a model (6)
I believe the answer is:
sitter
'a model' is the definition.
(I know that sitter is a type of model)
'it's very easy to be' is the wordplay.
'it's very easy' becomes 'ter' (I can't explain this - if you can you should believe this answer much more).
'to' says to put letters next to each other (I've seen this in other clues).
'be' becomes 'sit' (sitting is a kind of being).
'ter' after 'sit' is 'SITTER'.
Can you help me to learn more?
(Other definitions for sitter that I've seen before include "one can't stand?" , "Easy shot or catch" , "Dolly" , "Artist's model - an easy catch" , "Artist's model or child's minder" .)