Predator makes circle and then a fantastic arc (4)
I believe the answer is:
orca
'predator' is the definition.
(I have seen 'Large predator' mean 'orca' so perhaps 'predator' could also mean 'orca')
'circle and then a fantastic arc' is the wordplay.
'circle' becomes 'O' (O is a circle).
'and then' says to put letters next to each other (I've seen this in other clues).
'a fantastic' is an anagram indicator.
'arc' anagrammed gives 'rca'.
'o'+'rca'='ORCA'
'makes' acts as a link.
(Other definitions for orca that I've seen before include "Cor! a killer whale" , "swimmer in black and white" , "ship" , "27 [WHALE]" , "grampus" .)