Turn computers into a dishonest business (4)
I believe the answer is:
scam
'a dishonest business' is the definition.
(a dishonest scheme or enterprise)
'turn computers' is the wordplay.
'turn' says the letters should be written in reverse.
'computers' becomes 'Macs' (Apple Macs).
'macs' written backwards gives 'SCAM'.
'into' acts as a link.
(Other definitions for scam that I've seen before include "Fraud, trick (slang)" , "Rip-off" , "An informal swindle" , "Swindle (Slang)" , "Screw" .)