Beam when running back through state line (7)
I believe the answer is:
lanyard
'line' is the definition.
(lanyard is a kind of line)
'beam when running back through state' is the wordplay.
'beam when' becomes 'ray' (synonyms. I am not sure about the 'when' bit.).
'running back' says the letters should be written in reverse.
'through' indicates putting letters inside (inserted letters go through the word).
'state' becomes 'land' (synonyms).
'ray' back-to-front is 'yar'.
'yar' inserted inside 'land' is 'LANYARD'.
Can you help me to learn more?
(Other definitions for lanyard that I've seen before include "Cord with whistle attached" , "Dawdler" , "Cord worn around the neck by Boy Scout" , "Short rope used as a fastening" , "Neck cord holding whistle" .)