River following low ground covered with heath? (4)
I believe the answer is:
moor
'heath?' is the definition.
(both can mean a type of landscape)
'river following low' is the wordplay.
'river' becomes 'r' (abbreviation for river).
'following' is a charade indicator (letters next to each other).
'low' becomes 'moo' (both can mean to make the noise of a cow).
'r' put after 'moo' is 'MOOR'.
'ground covered with' is the link.
This may not be correct. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for moor that I've seen before include "Open expanse covered with heather and bracken" , "Heath; berth" , "Tract of uncultivated upland" , "Othello, perhaps" , "Open upland; tie up boat" .)