Motor in the open panel (8)
I believe the answer is:
outboard
'motor' is the definition.
(outboard motor is a kind of motor)
'open panel' is the wordplay.
'open' becomes 'out' (I've seen this in other clues).
'panel' becomes 'board' ('board' can be a synonym of 'panel').
'out'+'board'='OUTBOARD'
'in the' is the link.
(Other definitions for outboard that I've seen before include "Engine external to the boat" , "Small boat's motor" , "Engine attached to boat" , "Engine mounted at the stern of a small boat" , "Sort of motor" .)