Issue's about 101 descendants (6)
I believe the answer is:
scions
'descendants' is the definition.
(scion is a kind of descendant)
'issue's about 101' is the wordplay.
'issue's' becomes 'son's' (issue can mean someone's offspring).
'about' means one lot of letters goes inside another.
'101' becomes 'CI' (roman numerals).
'sons' placed around 'ci' is 'SCIONS'.
(Other definitions for scions that I've seen before include "Descendants, heirs" , "Descendents or heirs" .)