Did career thus mark the price of freedom? (6)
I believe the answer is:
ransom
'the price of freedom?' is the definition.
(price of freedom demanded by a kidnapper)
'did career thus mark' is the wordplay.
'did career' becomes 'ran' (to career can mean to run out of control).
'thus' becomes 'so' (synonyms).
'mark' becomes 'm'.
'ran'+'so'+'m'='RANSOM'
(Other definitions for ransom that I've seen before include "demand an extortionate price" , "Money demanded for the release of someone" , "Go beyond (a level)" , "Payment demanded for release of captive" , "Payment, eg to kidnapper" .)