Your child's boy (8)
I believe the answer is:
grandson
(Other definitions for grandson that I've seen before include "Male child of one's child" , "Male descendent" , "Junior relative" , "issue for daughter, perhaps" , "Daughter's boy" .)
I believe the answer is:
grandson
(Other definitions for grandson that I've seen before include "Male child of one's child" , "Male descendent" , "Junior relative" , "issue for daughter, perhaps" , "Daughter's boy" .)