Period of one's prime (6)
I believe the answer is:
heyday
(Other definitions for heyday that I've seen before include "Period of greatest vigour" , "Prime time?" , "Highest period in someone's career" , "golden age" , "Successful period" .)
I believe the answer is:
heyday
(Other definitions for heyday that I've seen before include "Period of greatest vigour" , "Prime time?" , "Highest period in someone's career" , "golden age" , "Successful period" .)