A relation of K-Pop? (8)
I believe the answer is:
Here is my best explanation:
'a relation' is the definition.
(granddad is a kind of relation)
'k-pop?' is the subsidiary indication.
'k' becomes 'grand' ('grand' can be a synonym of 'k').
'pop?' becomes 'dad' ('dad' can be a synonym of 'pop').
'of' is the link.
(Another definition for granddad that I've seen is "Familiar old man".)