Borderline alarming to be mixed up in this (8)
I believe the answer is:
marginal
'borderline' is the definition.
(I know that borderline can be written as marginal)
'alarming to be mixed up in this' is the wordplay.
'alarming' can be anagrammed to 'MARGINAL'.
But, I'm not sure how this is indicated.
Can you help me to learn more?
(Other definitions for marginal that I've seen before include "unsafe seat" , "Peripheral in alarming way" , "Very close (decision)" , "Of minor importance" , "On the fringes" .)