Warship oddly ignored a land mass (4)
I believe the answer is:
asia
'land mass' is the definition.
(I've seen this before)
'warship oddly ignored a' is the wordplay.
'oddly ignored' indicates alternate letters.
The alternate letters of 'warship' are 'asi'.
'asi'+'a'='ASIA'
(Other definitions for asia that I've seen before include "lands in the east" , "It has most of the earth's population" , "Continent in which India is situated" , "Part of the world" , "Populous area" .)