Discovering past life - yeah right! (2,2)
I believe the answer is:
as if
'yeah right' is the definition.
(I've seen this in another clue)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for as if that I've seen before include "a voice of doubt" , "Unbelievable!" , "highly unlikely" , "I very much doubt it!" , "Or though" .)