Dry heave (5)
I believe the answer is:
retch
'dry heave' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for retch that I've seen before include "Try to vomit" , "Strain throat as if vomiting" , "Sound and seem to vomit" , "Try to be sick" , "Strain as if to vomit" .)