Row over time to reveal pedigree (7)
I believe the answer is:
lineage
'pedigree' is the definition.
(I know that pedigree can be written as lineage)
'row over time' is the wordplay.
'row' becomes 'line' (as in a row of things).
'over' is a charade indicator (letters next to each other) (in a down clue, some letters go over others).
'time' becomes 'age' (an age is a period of time).
'line'+'age'='LINEAGE'
'to reveal' is the link.
(Other definitions for lineage that I've seen before include "Stock" , "Ancestral line as seen in eagle" , "The strain" , "Descent from ancestors" , "Genealogy" .)