Constellation next to Hercules (4)
I believe the answer is:
lyra
'constellation next to hercules' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for lyra that I've seen before include "Asriel's child" , "Group of stars" , "Constellation resembling a musical instrument" , "Constellation near Draco" , "Constellation representing instrument of Orpheus" .)