Some ships with radar uncovered weapon to the north (6)
I believe the answer is:
armada
'some ships' is the definition.
(group of ships)
'radar uncovered weapon to the north' is the wordplay.
'uncovered' means to look at the middle letters.
'weapon' becomes 'arm' (synonyms).
'to the north' means one lot of letters go next to another (some letters go above or north of others).
The central letters of 'radar' are 'ada'.
'ada' after 'arm' is 'ARMADA'.
'with' acts as a link.
(Other definitions for armada that I've seen before include "Spanish war fleet" , "Large number of ships (Spanish?)" , "Old Spanish fleet" , "Large Spanish fleet" , "Fighting unit" .)