Insanity, being about to book in Canadian province (8)
I believe the answer is:
manitoba
'canadian province' is the definition.
(Manitoba is an example)
'insanity being about to book' is the wordplay.
'insanity' becomes 'mania' (I've seen this before).
'being about' indicates putting letters inside.
'book' becomes 'b'.
'to'+'b'='tob'
'mania' placed around 'tob' is 'MANITOBA'.
'in' acts as a link.
(Other definitions for manitoba that I've seen before include "sparsely-populated province" , "Winnipeg area" , "Canadian lake" , "Is Oman a bit in Canada, strangely?" , "Canadian prairie province" .)