Heath-covered tract (4)
I believe the answer is:
moor
'heath-covered tract' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for moor that I've seen before include "Open land - secure a boat - North African" , "Secure ship with cables" , "eg Ilkley, Othello" , "Heathery upland" , "Expanse of uncultivated upland" .)