The whole of the New Testament set in Ireland? (6)
I believe the answer is:
entire
'the whole' is the definition.
(I've seen this before)
'new testament set in ireland?' is the wordplay.
'new testament' becomes 'nt'.
'set in' indicates putting letters inside.
'ireland?' becomes 'Eire' (poetic name for Ireland).
'nt' placed within 'eire' is 'ENTIRE'.
'of the' is the link.
(Other definitions for entire that I've seen before include "excluding nothing" , "porter" , "With no part left out" , "Whole; absolute" , "Full, intact" .)