Beat back in time relatively speaking (6)
I believe the answer is:
agnate
'relatively speaking' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'beat back in time' is the wordplay.
'beat' becomes 'tan' (tan can mean to beat or hit).
'back' says the letters should be written backwards.
'in' is an insertion indicator.
'time' becomes 'age' (an age is a period of time).
'tan' back-to-front is 'nat'.
'nat' going inside 'age' is 'AGNATE'.
Can you help me to learn more?
(Other definitions for agnate that I've seen before include "Get an A (anag.)" , "Relative" , "Descended from the same male ancestor" , "Related through male descent on father's side (6)" .)