A nervous throw? (3)
I believe the answer is:
shy
I believe this clue is a double definition.
'a nervous' is the first definition.
(I've seen this in other clues)
'throw?' is the second definition.
(I know that shy is a more specific form of the action the throw)
(Other definitions for shy that I've seen before include "Short of" , "Pitch" , "Quick throw" , "Throw in bashful way" , "Chary" .)