Dad learnt about being fatherly (8)
I believe the answer is:
parental
'fatherly' is the definition.
(thesaurus)
'dad learnt about' is the wordplay.
'dad' becomes 'pa' (both can mean one's father).
'about' indicates anagramming the letters.
'learnt' anagrammed gives 'rental'.
'pa'+'rental'='PARENTAL'
'being' is the link.
(Other definitions for parental that I've seen before include "of old man and woman" , "Relating to mother and father" , "like mum and dad" , "of some older relatives" , "of father, perhaps" .)