Snarl in the first corner (6)
I believe the answer is:
tangle
'snarl' is the definition.
(I know that snarl can be written as tangle)
'the first corner' is the wordplay.
'the first' becomes 't' (1st letter of 'the').
'corner' becomes 'angle' (eg a corner of a shape).
't'+'angle'='TANGLE'
'in' is the link.
(Other definitions for tangle that I've seen before include "Get knotted!" , "Enmesh, snarl up" , "Confused state; seaweed" , "Mix-up" , "Twist into a confused mass, or informally fight with" .)