Good African currency’s ready for younger relative (8)
I believe the answer is:
grandson
'younger relative' is the definition.
'good african currency's ready' is the wordplay.
'good' becomes 'g' (abbreviation).
'african currency's' becomes 'rands'.
'ready' becomes 'on' (if a device is on it is ready for use).
'g'+'rands'+'on'='GRANDSON'
'for' acts as a link.
(Other definitions for grandson that I've seen before include "Junior relative" , "Dons rang (anag) - relative" , "Male offspring, third generation (8)" , "Male child of one's child" , "Daughter's boy" .)