Steal from orchard that is behind (6)
I believe the answer is:
scrump
'steal from orchard' is the definition.
(I've seen this before)
'that is behind' is the wordplay.
'that is' becomes 'sc' (abbrv. for Latin scilicet; 'namely').
'behind' becomes 'rump' ('rump' can be a synonym of 'behind'**).
'sc'+'rump'='SCRUMP'
(Other definitions for scrump that I've seen before include "Steal apples from trees" , "steal from farmer" , "Nick in garden" , "swipe them?" , "Steal (fruit) from an orchard" .)