Guess the car I’m in (8)
I believe the answer is:
estimate
'guess' is the definition.
(I know that guess can be written as estimate)
'car i'm in' is the wordplay.
'car' becomes 'estate' (type of car).
'in' means one lot of letters goes inside another.
'estate' enclosing 'im' is 'ESTIMATE'.
'the' is the link.
(Other definitions for estimate that I've seen before include "Gauge - approximation" , "Tease Tim (anag.)" , "damage" , "Calculate roughly" , "Rough cost" .)