Book hour hosted by ship's guide (8)
I believe the answer is:
thriller
'book' is the definition.
(I have seen 'Exciting book ' mean 'thriller' so perhaps 'book' could also mean 'thriller')
'hour hosted by ship's guide' is the wordplay.
'hour' becomes 'hr' (abbreviation).
'hosted by' is an insertion indicator.
'ship's guide' becomes 'tiller' (I am not sure about this - if you are sure you should believe this answer much more).
'hr' going inside 'tiller' is 'THRILLER'.
Can you help me to learn more?
(Other definitions for thriller that I've seen before include "exciting work" , "Genre of novel" , "Exciting story or film" , "Very exciting contest" , "Exciting novel or film" .)