Book somewhere to watch big game perhaps (7)
I believe the answer is:
reserve
'book' is the definition.
(as in booking or reserving in advance)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for reserve that I've seen before include "Modesty- store" , "Book - substitute player" , "Lack of openness" , "Reticence" , "One on bench" .)