Nearly raring to go in study (4)
I believe the answer is:
read
'study' is the definition.
(I know that study can be written as read)
'nearly raring to go' is the wordplay.
'nearly' means to remove the last letter.
'raring to go' becomes 'ready' (I've seen this in another clue).
'ready' with its last letter taken away is 'READ'.
'in' acts as a link.
(Other definitions for read that I've seen before include "Stomach" , "Undertake a course of study" , "Check, emend (proof)" , "Lecture" , "Con" .)