Line that's touching sun-affected guy (7)
I believe the answer is:
tangent
'line' is the definition.
(I know that tangent is a type of straight line)
'touching sun-affected guy' is the wordplay.
I cannot really understand how this works, but
'sun' could be 'tan' (both can mean to get a sun tan) and 'tan' is found in the answer.
'guy' could be 'gent' (I've seen this in another clue) and 'gent' is found within the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
'that's' acts as a link.
Can you help me to learn more?
(Other definitions for tangent that I've seen before include "Line that touches curve without crossing it" , "Line touching curve at one point" , "mostly irrelevant item" , "Straight line resting on a circle" , "Trig ratio" .)