Spot of land in the sea (4)
I believe the answer is:
isle
'spot of land in the sea' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for isle that I've seen before include "Man, possibly" , "Geographic location" , "Rum, for example" , "eg Skye" , "Of Man or Youth, for example" .)