Magnitude points to a triangle (7)
I believe the answer is:
scalene
'triangle' is the definition.
(scalene triangle is a kind of triangle)
'magnitude points' is the wordplay.
'magnitude' becomes 'scale' (I have seen 'Relative magnitude' mean 'scale' so perhaps 'magnitude' could also mean 'scale').
'points' becomes 'ne' (North and East).
'scale'+'ne'='SCALENE'
'to a' acts as a link.
(Other definitions for scalene that I've seen before include "(Of triangle) with no sides equal" , "(Of triangle) having three unequal sides" , "not having evenly matched sides" , "Neither equilateral nor isosceles" , "(Of triangle) with each side of a different length" .)