Two together protect English border from giant (8)
I believe the answer is:
behemoth
'giant' is the definition.
('behemoth' can be a synonym of 'giant')
'two together protect english border' is the wordplay.
'two together' becomes 'both' (I've seen this before).
'protect' means one lot of letters goes inside another.
'english' becomes 'e' (abbreviation).
'border' becomes 'hem' (I've seen this before).
'e'+'hem'='ehem'
'both' going around 'ehem' is 'BEHEMOTH'.
'from' is the link.
(Other definitions for behemoth that I've seen before include "Gigantic beast in Job" , "Anything abnormally large and powerful" , "Huge or monstrous creature" , "Something abnormally large and powerful" , "Abnormally large creature" .)