They open, exceptionally, for a new convert (8)
I believe the answer is:
neophyte
'a new convert' is the definition.
(I've seen this before)
'they open exceptionally' is the wordplay.
'exceptionally' indicates anagramming the letters.
'they'+'open'='theyopen'
'theyopen' is an anagram of 'NEOPHYTE'.
'for' is the link.
(Other definitions for neophyte that I've seen before include "They open for a new convert" , "raw recruit" , "Initiate" , "Pet honey for a religious novice" , "One's just taken orders" .)