Upbringing of awkward runt on river (7)
I believe the answer is:
nurture
'upbringing' is the definition.
(nurture is a kind of upbringing)
'awkward runt on river' is the wordplay.
'awkward' indicates anagramming the letters.
'on' means one lot of letters go next to another.
'river' becomes 'ure' (I have seen 'River of Wensleydale ' mean 'ure' so perhaps 'river' could also mean 'ure'**).
'runt' with letters rearranged gives 'nurt'.
'nurt'+'ure'='NURTURE'
'of' is the link.
(Other definitions for nurture that I've seen before include "Encourage to develop" , "Cherish (an ambition)" , "Feed - support" , "Care for, feed, educate" , "Train" .)