Granddaughter perhaps runs with joy (8)
I believe the answer is:
relation
'granddaughter perhaps' is the definition.
(granddaughter is a type of relation)
'runs with joy' is the wordplay.
'runs' becomes 'r' (cricket abbreviation).
'with' is a charade indicator (letters next to each other).
'joy' becomes 'elation' (elation is a kind of joy).
'r'+'elation'='RELATION'
(Other definitions for relation that I've seen before include "Mum or dad" , "Link" , "statement" , "Grandchild, perhaps" , "Affinity" .)