Plan a little hideaway (4)
I believe the answer is:
idea
'plan' is the definition.
(both can mean an intention)
'a little hideaway' is the wordplay.
'a little' indicates a hidden word.
'IDEA' is hidden in the letters of 'hideaway'.
(Other definitions for idea that I've seen before include "A suspicion of" , "Notion, concept" , "Notion in the mind" , "Inkling" , "Brainwave" .)