Killer sea creature minutes away from Spanish island (4)
I believe the answer is:
orca
'killer sea creature' is the definition.
(term for a killer whale)
'minutes away from spanish island' is the wordplay.
'minutes' becomes 'min' (short for minutes).
'away from' is a deletion indicator.
'spanish island' becomes 'Minorca'.
'minorca' with 'min' taken out is 'ORCA'.
(Other definitions for orca that I've seen before include "Danger for swimmers" , "Sea creature" , "27 [WHALE]" , "Massive killer" , "Marine creature" .)