Jemmy, lever (7)
I believe the answer is:
crowbar
This clue is a double definition.
'jemmy' is the first definition.
(I've seen this before)
'lever' is the second definition.
(crowbar is a kind of lever)
(Other definitions for crowbar that I've seen before include "Heavy iron lever" , "In America, one prizes" , "Burglar's tool, perhaps" , "Powerful opener" , "Iron lever for prising" .)