Discovered in bundle theory - the flowery underground segment that helps you forget your life (5)
I believe the answer is:
lethe
'the flowery underground segment that helps you forget your life' is the definition.
I can't judge whether this definition defines the answer.
'discovered in bundle theory' is the wordplay.
'discovered' says the answer is hidden in the clue (remove the letters covering the answer in the clue).
'LETHE' is hidden in the letters of 'in bundle theory'.
Can you help me to learn more?
(Other definitions for lethe that I've seen before include "River whose waters caused the souls of the dead to forget completely their life on Earth" , "In Greek myth, the river of forgetfulness flowing through Hades" , "Ethel's mythical river of forgetfulness" , "Mythological river in Hades" , "River whose waters caused forgetfulness" .)