Nasty ice on side bed -- problem in the earliest garden? (12)
I believe the answer is:
disobedience
'problem in the earliest garden?' is the definition.
(reference to the Garden of Eden)
'nasty ice on side bed' is the wordplay.
'nasty' is an anagram indicator.
'ice'+'on'+'side'+'bed'='iceonsidebed'
'iceonsidebed' with letters rearranged gives 'DISOBEDIENCE'.
(Other definitions for disobedience that I've seen before include "Lack of submission" , "Refusal to do what one is told" , "Failure to take orders" , "Defiance, unruliness" , "Insubordination" .)