Flood from river covering moor regularly (7)
I believe the answer is:
torrent
'flood' is the definition.
(I've seen this before)
'river covering moor regularly' is the wordplay.
'river' becomes 'trent' (River Trent).
'covering' indicates putting letters inside.
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
The alternate letters of 'moor' are 'or'.
'trent' going around 'or' is 'TORRENT'.
'from' acts as a link.
(Other definitions for torrent that I've seen before include "Outburst" , "Heavy stream" , "Rush of water" , "Violently fast stream of water" , "Inundation" .)