I daren't exchange one car for another (5,2)
I believe the answer is:
trade in
'one car for another' is the definition.
I can't judge whether this definition defines the answer.
'i daren't exchange' is the wordplay.
'exchange' indicates anagramming the letters.
'i'+'darent'='idarent'
'idarent' anagrammed gives 'TRADE-IN'.
Can you help me to learn more?
(Other definitions for trade in that I've seen before include "Part-exchange" , "valuation of part of deal" , "Item used in partial payment" , "As part of deal, exchange" , "Get some money back" .)