Monster in dread, wiping out a climbing plant (8)
I believe the answer is:
werewolf
'monster' is the definition.
(werewolf is a kind of monster)
'dread wiping out a climbing plant' is the wordplay.
'dread' becomes 'awe' (I've seen this before).
'wiping out' is a deletion indicator.
'climbing' shows that the letters should be reversed in order (in a down clue, letters climb up).
'plant' becomes 'flower' (flower is a kind of plant**).
'awe' with 'a' taken away is 'we'.
'flower' back-to-front is 'rewolf'.
'we'+'rewolf'='WEREWOLF'
'in' is the link.
(Other definitions for werewolf that I've seen before include "Person beleived to be able to assume lupine form" , "Hairy beast" , "Person who becomes a monster when the moon is full" , "man going wild occasionally" , "A monster able to change from human into a rapacious animal" .)