Hokusai's fifth boat illustration (6)
I believe the answer is:
sketch
'illustration' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Perhaps you can see a link between them that I can't see?
'hokusai's fifth boat' is the wordplay.
'hokusai's fifth' becomes 's' (5th letter of 'hokusai').
'boat' becomes 'ketch' (ketch is a kind of sailing vessel).
's'+'ketch'='SKETCH'
Can you help me to learn more?
(Other definitions for sketch that I've seen before include "draft" , "Portrait" , "bit of a performance" , "Rough outline" , "Brief outline or drawing" .)