Novel heroine embraces rustic new body (9)
I believe the answer is:
thickness
'body' is the definition.
(thickness is a kind of body)
'novel heroine embraces rustic new' is the wordplay.
'novel heroine' becomes 'tess' (I have seen 'Hardy heroine ' mean 'tess' so perhaps 'heroine' could also mean 'tess'. I am not sure about the 'novel' bit.).
'embraces' means one lot of letters goes inside another.
'rustic' becomes 'hick' (hick is a kind of rustic).
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'hick'+'n'='hickn'
'tess' enclosing 'hickn' is 'THICKNESS'.
Can you help me to learn more?
(Other definitions for thickness that I've seen before include "Dimension through an object" , "Diameter" , "Dimension from front to back" , "Breadth" , "Mass from front to back" .)