Planned action without notice (8)
I believe the answer is:
designed
'planned' is the definition.
('design' can be a synonym of 'plan')
'action without notice' is the wordplay.
'action' becomes 'deed' (deed is a kind of action).
'without' means one lot of letters goes inside another ('without' can be similar in meaning to 'outside').
'notice' becomes 'sign' (I've seen this before**).
'deed' placed around 'sign' is 'DESIGNED'.
(Other definitions for designed that I've seen before include "Conceived and drew something" , "Make a drawing or blueprint" , "Intended; drew" , "Planned or created" , "Meant" .)