A relative lack of energy in synthesised androgens (8)
I believe the answer is:
grandson
'a relative' is the definition.
(grandson is a type of relative)
I don't understand the remainder of the clue.
(Other definitions for grandson that I've seen before include "Junior relative" , "Male child of one's child" , "Young male descendant" , "issue for daughter, perhaps" , "Dons rang (anag) - relative" .)