Hint, having book set in 1728, say (4)
I believe the answer is:
cube
'set in 1728 say' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe you can see an association between them that I can't see?
'hint having book' is the wordplay.
'hint' becomes 'cue' (I've seen this before).
'having' means one lot of letters goes inside another.
'book' becomes 'b'.
'cue' enclosing 'b' is 'CUBE'.
Can you help me to learn more?
(Other definitions for cube that I've seen before include "Three-dimensional square" , "nine?" , "Square-sided body" , "In maths, the third power of a quantity" , "Regular solid figure" .)