Called out Grant's descendants (4)
I believe the answer is:
seed
'descendants' is the definition.
(seed can mean someone's offspring)
'called out grant's' is the wordplay.
'called out' indicates a 'sounds like' (homophone) clue.
'grant' becomes 'cede' (synonyms).
'cede' is a homophone of 'SEED'.
(Other definitions for seed that I've seen before include "See 19" , "Kernel" , "Germ; beginning" , "one very much fancied" , "Pip - source - children" .)