Line of sunbeam reflected in Earth (7)
I believe the answer is:
lanyard
'line of sunbeam' is the definition.
'lanyard' can be an answer for 'line' (lanyard is a kind of line). I am not certain of the 'of sunbeam' bit.
'reflected in earth' is the wordplay.
'reflected in' becomes 'lan' (I can't explain this - if you can you should give a lot more credence to this answer).
'earth' becomes 'yard' (I've seen this before).
'lan'+'yard'='LANYARD'
Can you help me to learn more?
(Other definitions for lanyard that I've seen before include "Line for extending or fastening ship's rigging" , "Cord worn round neck" , "Part of rigging" , "Dawdler" , "Neck cord holding whistle" .)