Sketches include boat (5)
I believe the answer is:
ketch
'boat' is the definition.
(ketch is a type of sailing boat)
'sketches include' is the wordplay.
'include' says the answer is hidden in the clue.
'KETCH' can be found hidden inside 'sketches'.
(Other definitions for ketch that I've seen before include "Small two-master sailing vessel" , "Two-masted sailing ship" , "Two-masted sailing vessel" , "The craft" , "2-masted boat" .)