Relative on the male side has silver, not available initially though, I comprehend (7)

'relative on the male side' is the definition.
Both the definition and answer are adjectives. Perhaps you can see a link between them that I can't see?

'silver not available initially though i comprehend' is the wordplay.
'silver' becomes 'Ag' (Ag is the chemical symbol for silver).
'not available' becomes 'na' (abbreviation for not available).
'initially' indicates taking the first letters.
'i comprehend' becomes 'ic' (this might be a standard abbreviation of which I'm unaware).
The initial letter of 'though' is 't'.
'ag'+'na'+'t'+'ic'='AGNATIC'

'has' acts as a link.

Can you help me to learn more?