Discern tangled scrub (7)
I believe the answer is:
rescind
'scrub' is the definition.
(I've seen this before)
'discern tangled' is the wordplay.
'tangled' indicates anagramming the letters.
'discern' is an anagram of 'RESCIND'.
(Other definitions for rescind that I've seen before include "Annul - discern (anag)" , "Revoke (a law/order)" , "Annul using cinders" , "Set aside law" , "Scrub" .)