Relating to an offspring (6)
I believe the answer is:
filial
'relating to an offspring' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for filial that I've seen before include "Of or due from son or daughter, perhaps affection" , "Relating to sons or daughters" , "Relating to a daughter or son" , "Concerned with issue" , "next generation" .)