Member of old Jewish fraternity — she's frequently seen going out (6)
I believe the answer is:
essene
'member of old jewish fraternity' is the definition.
The definition suggests a singular noun which matches the answer.
'she's frequently seen going out' is the wordplay.
'frequently' means one should take alternating letters (letters selected at a regular frequency).
'going out' indicates an anagram (out can mean wrong or inaccurate).
The alternate letters of 'she' are 'se'.
'se'+'seen'='seseen'
'seseen' is an anagram of 'ESSENE'.
Can you help me to learn more?
(Other definitions for essene that I've seen before include "Zealot" , "Ascetic type" , "Jewish frater" , "Early Jewish ascetic" , "Old Jewish sectarian" .)