Group in Dublin eager to establish ancestry (7)
I believe the answer is:
lineage
'ancestry' is the definition.
(I know that ancestry can be written as lineage)
'group in dublin eager' is the wordplay.
'group in' says the answer is hidden in the clue (a group of letters hidden in the clue).
'LINEAGE' can be found hidden inside 'dublin eager'.
'to establish' acts as a link.
(Other definitions for lineage that I've seen before include "Old family members" , "Line of descendants of an ancestor" , "Ancestral line as seen in eagle" , "The strain" , "Line of descent or ancestry" .)