Nymph who loved Narcissus (4)
I believe the answer is:
echo
'nymph who loved narcissus' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for echo that I've seen before include "Nymph; E (radio comms.)" , "Greek nymph, spurned by Narcissus, who pined away until only her voice remained" , "Audio effect" , "Send back" , "Reflect in Czechoslovakia" .)