The sort of prospect supplied by ramblers, for instance (4)
I believe the answer is:
rosy
If this is the answer I cannot explain how the clue works.
Can you help me to learn more?
(Other definitions for rosy that I've seen before include "Healthy-looking" , "Pinkish; healthy" , "Of the future, promising like flower" , "Blushing - optimistic" , "lady" .)