Unknown state car tours Belgium (5)
I believe the answer is:
limbo
'unknown state' is the definition.
'limbo' can be an answer for 'state' (limbo is a kind of state). I'm unsure of the 'unknown' bit.
'car tours belgium' is the wordplay.
'car' becomes 'limo' (limo is a kind of car).
'tours' is an insertion indicator (to tour can mean to go around).
'belgium' becomes 'B' (international vehicle registration code).
'limo' enclosing 'b' is 'LIMBO'.
Can you help me to learn more?
(Other definitions for limbo that I've seen before include "nowhere in particular" , "Medieval Christian abode for unbaptised souls" , "Place of suspense" , "State of waiting in uncertainty" , "This has lowered bar" .)