Test version of software (4)
I believe the answer is:
beta
'test version of software' 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 "Second Greek letter, B" , "software under test" , "less than perfect mark" , "Greek character - not quite top-notch" , "Character between alpha and gamma" .)