I hadn’t turned round paintings (5)
I believe the answer is:
tondi
'paintings' is the definition.
(plural of tondo, a circular painting)
'i hadn't turned round' is the wordplay.
'i hadn't' becomes 'I'd not' (both are contractions of 'I had not').
'turned round' is a reversal indicator.
'idnot' in reverse letter order is 'TONDI'.
(Other definitions for tondi that I've seen before include "paintings" , "carving in circles" , "Circular carvings" .)