To buy it, must one be in credit? (3)
I believe the answer is:
car
'to buy it must' is the definition.
I can't judge whether this definition defines the answer.
'one be in credit?' is the wordplay.
'one' becomes 'a' (a thing is one thing).
'be in' indicates putting letters inside.
'credit?' becomes 'cr' (abbreviation).
'a' placed inside 'cr' is 'CAR'.
Can you help me to learn more?
(Other definitions for car that I've seen before include "Railway carriage; vehicle" , "Road vehicle; rail coach" , "Wheeled vehicle" , "Private vehicle" , "Private transport" .)