Early software version (5)
(Other definitions for alpha that I've seen before include "First letter of the Greek alphabet" , "First in order of importance (for a Greek?)" , "Burrowing American rodent" , "Top star" , "Most prominent star" .)
'early software 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 "testing stage" , "software under test" , "Second highest grade of mark" , "Second-class" , "Old character" .)