Greek nymph who pined away until only her voice remained (4)
I believe the answer is:
echo
'greek nymph who pined away until only her voice remained' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for echo that I've seen before include "Repetition by reflection" , "Nymph; E (radio comms.)" , "Nymph (only able to repeat the last words of others)" , "Sound bouncing back" , "Reflection of sound - Greek nymph" .)