Exploit Oscar during unusual free trip (9)
I believe the answer is:
profiteer
'exploit' is the definition.
(to profiteer is to exploit for profit)
'oscar during unusual free trip' is the wordplay.
'oscar' becomes 'O' (phonetic alphabet: alpha, bravo, charlie etc.).
'during' indicates putting letters inside.
'unusual' indicates anagramming the letters.
'free'+'trip'='freetrip'
'freetrip' with letters rearranged gives 'prfiteer'.
'o' placed within 'prfiteer' is 'PROFITEER'.
(Other definitions for profiteer that I've seen before include "One making excessive gains from trading" , "Overcharge" , "Make too much money" , "Gain unfairly" , "Racketeer" .)