Hard to get into bird book? (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')
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for thriller that I've seen before include "exciting work" , "best-selling album" , "suspenseful book?" , "Exciting novel or film" , "A detective story can be sensational" .)