Clue: In rebellious age, sailor came to prominence (5)
Answer: AROSE
Explanation: In rebellious age, sailor came to prominence (5)
**O.S.** (ordinary seaman, so "sailor") *in* **<=ERA** (rebellious "age") 
*Although it is generally accepted in Crosswordland, I don't like "rebellious" as a reversal indicator, as it requires an extra step (the solver has to think "rebellious means up, so you have to reverse the letters", which, to my mind, is just as unfair as an indirect anagram)