Key turned in panic is abandoned (5)
I believe the answer is:
basic
'key' is the definition.
(I've seen this before)
'turned in panic is abandoned' is the wordplay.
'turned' shows that the letters should be reversed in order.
'in' says the answer is hidden in the clue.
'cisab' can be found hidden inside 'panic is abandoned'.
'cisab' in reverse letter order is 'BASIC'.
(Other definitions for basic that I've seen before include "At the simplest level" , "Fundamental -- early computer language" , "Straightforward" , "Fundamental instruction's" , "vital" .)