Impatient to get started (5)
I believe the answer is:
eager
'impatient to get started' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for eager that I've seen before include "Keen, avid" , "Longing to see" , "Enthusiastic, raring to go" , "Whole-hearted" , "Thirsty" .)