Gem of a diva met hysterical fans secretly (8)
I believe the answer is:
amethyst
'gem' is the definition.
(amethyst is a kind of gem)
'diva met hysterical fans secretly' is the wordplay.
'secretly' indicates a hidden word.
'AMETHYST' is hidden within 'diva met hysterical fans'.
'of a' is the link.
(Other definitions for amethyst that I've seen before include "Transparent bluish quartz" , "Bluish-violet 3" , "Type of quartz" , "Purple gem" , "rock" .)