Not sculpture in concrete, it would seem (8,3)
I believe the answer is:
abstract art
'not sculpture' is the definition.
'abstract art' can be an answer for 'sculpture' (thesaurus). I am not sure about the 'not' bit.
'concrete it would seem' is the wordplay.
I cannot quite understand how this works, but
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is found within the answer.
'seem' could be 'act' (I've seen this in another clue) and 'act' is found in the answer.
This explanation may well be incorrect...
'in' acts as a link.
Can you help me to learn more?
(Another definition for abstract art that I've seen is " Nonrepresentational paintings, sculpture etc".)