One gets the setter to adopt a good appearance (5)
I believe the answer is:
image
'appearance' is the definition.
(image is a kind of appearance)
'one gets the setter to adopt a good' is the wordplay.
'one' becomes 'i' (Roman numeral).
'gets' says to put letters next to each other.
'the setter' becomes 'me' (the setter of the clue).
'to adopt' indicates putting letters inside.
'a good' becomes 'ag' (I've seen this in other clues**).
'me' enclosing 'ag' is 'mage'.
'i'+'mage'='IMAGE'
(Other definitions for image that I've seen before include "Public persona" , "Photo or likeness" , "Visible impression" , "public perception" , "Picture (involving one letter change from 10)" .)