Rest somewhere on course (3)
I believe the answer is:
lie
This clue might be a double definition.
'rest somewhere' is the first definition.
'lie' can be an answer for 'rest' (synonyms). I am not sure about the 'somewhere' bit.
'course' is the second definition.
(thesaurus)
'on' is the link.
Can you help me to learn more?
(Other definitions for lie that I've seen before include "Tell porkies" , "Perjure" , "Fabrication" , "Fib - be prone" , "Be prostrate" .)