A challenge to include whiskey in selling software (6)
I believe the answer is:
adware
'selling software' is the definition.
'a challenge to include whiskey' is the wordplay.
'challenge' becomes 'dare' (daring is a kind of challenging).
'to include' indicates putting letters inside.
'whiskey' becomes 'w' (alpha bravo charlie delta ...).
'dare' placed around 'w' is 'dware'.
'a'+'dware'='ADWARE'
'in' acts as a link.
(Other definitions for adware that I've seen before include "web advertising programs" , "computer plug-ins?" , "computer programs" , "commercial apps" .)