Release computer key in regret (6)
I believe the answer is:
rescue
'release' is the definition.
(thesaurus)
'computer key in regret' is the wordplay.
'computer key' becomes 'esc' (the Escape key on a keyboard).
'in' is an insertion indicator.
'regret' becomes 'rue' (to rue something is to regret it).
'esc' placed within 'rue' is 'RESCUE'.
(Other definitions for rescue that I've seen before include "saving" , "Get over, on top of" , "Free - recovery" , "Save from harm" , "Secure (anag) - deliverance" .)