Test version (4)
I believe the answer is:
beta
'test version' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for beta that I've seen before include "Greek character - not quite top-notch" , "Character between alpha and gamma" , "Second-rate" , "In a constellation, a star second in brightness" , "Second-class" .)