Cut down, as many admit (4)
I believe the answer is:
mown
'cut down' is the definition.
(I've seen this in another clue)
'many admit' is the wordplay.
'many' becomes 'm' (Roman numeral for a thousand).
'admit' becomes 'own' (own can mean to admit or acknowledge).
'm'+'own'='MOWN'
'as' is the link.
(Other definitions for mown that I've seen before include "Cut down with a blade" , "(Of grass) cut" , "Block of cast metal" .)