Period of waiting in car without book (5)
I believe the answer is:
limbo
'period of waiting' is the definition.
(being in limbo is waiting)
'car without book' is the wordplay.
'car' becomes 'limo' (limo is a kind of car).
'without' indicates putting letters inside ('without' can be similar in meaning to 'outside').
'book' becomes 'b' (abbreviation for book).
'limo' placed around 'b' is 'LIMBO'.
'in' acts as a link.
(Other definitions for limbo that I've seen before include "(Under bar) dance" , "Former state as for unbaptised souls" , "(Between) two extremes" , "Where waiters are" , "Pole dance" .)