Relay from fathers to offspring (4,2)
I believe the answer is:
pass on
'relay' is the definition.
(I know that relay is a more specific form of the action pass on)
'fathers to offspring' is the wordplay.
'fathers' becomes 'pas' (pa is a kind of father).
'to offspring' becomes 'son' (male offspring).
'pas'+'son'='PASS ON'
'from' acts as a link.
(Other definitions for pass on that I've seen before include "Bequeath" , "go forward" , "Hand over - die" , "Refuse" .)