Cardinal scratching head still (4)
I believe the answer is:
even
'still' is the definition.
(I know that still can be written as even)
'cardinal scratching head' is the wordplay.
'cardinal' becomes 'seven' (seven is a cardinal number).
'scratching head' means to remove the first letter (the word's head is removed).
'seven' with its initial letter taken off is 'EVEN'.
(Other definitions for even that I've seen before include "time of day" , "Flat - yet" , "time when sun goes down for the poet" , "Level, par" , "Not odd; flat" .)