Marconi goes out to a Spanish island (7)
I believe the answer is:
minorca
'spanish island' is the definition.
(Minorca is a Spanish island)
'marconi goes out' is the wordplay.
'goes out' is an anagram indicator.
'marconi' is an anagram of 'MINORCA'.
'to a' is the link.
(Other definitions for minorca that I've seen before include "One of Balearic islands" , "Land in Balearics" , "Mediterranean island" , "Balearic island; O, cram in (anag.)" , "Balearic island (Eng. sp.)" .)