Grandchild, perhaps, bringing monarch great joy (8)
I believe the answer is:
relation
'grandchild perhaps' is the definition.
(grandchild is a kind of relation)
'monarch great joy' is the wordplay.
'monarch' becomes 'r' (r is abbreviation for rex).
'great joy' becomes 'elation' (I've seen this before).
'r'+'elation'='RELATION'
'bringing' is the link.
(Other definitions for relation that I've seen before include "Affinity" , "Reference" , "Kinsman; narrative" , "Mum or dad" , "Grandchild, perhaps" .)