Passing on yearling for training (8)
I believe the answer is:
relaying
'passing on' is the definition.
(relaying is a kind of passing on)
'yearling for training' is the wordplay.
'for training' indicates anagramming the letters ('train' can mean to shape the growth of a plant).
'yearling' with letters rearranged gives 'RELAYING'.
(Other definitions for relaying that I've seen before include "Communicating" , "Broadcasting" .)