Headless spook gives concern (4)
I believe the answer is:
care
'concern' is the definition.
(I know that concern can be written as care)
'headless spook' is the wordplay.
'headless' means to remove the first letter.
'spook' becomes 'scare' (I've seen this in another clue).
'scare' with its first letter removed is 'CARE'.
'gives' is the link.
(Other definitions for care that I've seen before include "Mind" , "Have concern or regard" , "Worry" , "Be concerned or nurse" , "Have affection (for)" .)