Help net a surprisingly large creature (8)
I believe the answer is:
elephant
'large creature' is the definition.
(large animal)
'help net a surprisingly' is the wordplay.
'surprisingly' indicates anagramming the letters.
'help'+'net'+'a'='helpneta'
'helpneta' is an anagram of 'ELEPHANT'.
(Other definitions for elephant that I've seen before include "Large beast" , "Source of ivory" , "Then leap (anag.)" , "Large animal (in the room?)" , "Large pachyderm" .)