Touching line from bronze chap (7)
I believe the answer is:
tangent
'touching line' is the definition.
(I've seen this before)
'bronze chap' is the wordplay.
'bronze' becomes 'tan' ('tan' can be a synonym of 'bronze').
'chap' becomes 'gent' (I've seen this in other clues**).
'tan'+'gent'='TANGENT'
'from' acts as a link.
(Other definitions for tangent that I've seen before include "Completely different line of thought - trigonometrical function" , "Trig ratio" , "seen to be touching" , "A new line of thought" , "Straight line touching a circle" .)