Sublimity of some poetry son’s absorbing frequently (9)
I believe the answer is:
loftiness
'sublimity' is the definition.
The answer and definition can be both human attributes as well as being singular nouns.
Perhaps you can see an association between them that I don't see?
'some poetry son's absorbing frequently' is the wordplay.
'some poetry' becomes 'lines' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'absorbing' is an insertion indicator.
'frequently' becomes 'oft' (oft can mean frequently, eg oft-quoted).
'lines'+'s'='liness'
'liness' enclosing 'oft' is 'LOFTINESS'.
'of' acts as a link.
Can you help me to learn more?
(Other definitions for loftiness that I've seen before include "Arrogance" , "Impressive height; nobility (of manner)" , "Pomposity" .)