Devise mark with intersecting lines (5)
I believe the answer is:
hatch
I believe this clue is a double definition.
'devise' is the first definition.
(as in hatching a plan)
'mark with intersecting lines' is the second definition.
(to hatch is to shade an area with lines)
(Other definitions for hatch that I've seen before include "Emerge from egg - opening" , "Sit on eggs" , "Dream up" , "Deck opening; (egg) open" , "Incubate - plan" .)