Quiet girl absorbing a film (6)
I believe the answer is:
patina
'film' is the definition.
(both can mean a layer)
'quiet girl absorbing a' is the wordplay.
'quiet' becomes 'p' (music symbol for 'piano', ie soft or quiet).
'girl' becomes 'tina' (girl's name).
'absorbing' indicates putting letters inside.
'p'+'tina'='ptina'
'ptina' going around 'a' is 'PATINA'.
(Other definitions for patina that I've seen before include "Sheen acquired from constant handling" , "A surface gloss produced by age" , "thin coating" , "Fine layer on the surface, laid down over time" , "Surface film formed by age" .)