Quietly distributing another book of the Bible that describes the Virgin Birth (15)
I believe the answer is:
parthenogenesis
'the virgin birth' is the definition.
(I've seen this before)
'quietly distributing another book of the bible' is the wordplay.
'quietly' becomes 'p' (p for piano and quiet).
'distributing' indicates an anagram.
'book of the bible' becomes 'genesis' (I've seen this before).
'another' anagrammed gives 'artheno'.
'p'+'artheno'+'genesis'='PARTHENOGENESIS'
'that describes' is the link.
(Other definitions for parthenogenesis that I've seen before include "Means to reproduce" , "Way of making young" , "virgin birth" .)