Almost completed northern range (4)
I believe the answer is:
oven
'range' is the definition.
(I've seen this before)
'almost completed northern' is the wordplay.
'almost' means to remove the last letter (most of the word but not all of it).
'completed' becomes 'over' (synonyms).
'northern' becomes 'n' (abbreviation e.g. N. Ireland).
'over' with its last letter removed is 'ove'.
'ove'+'n'='OVEN'
(Other definitions for oven that I've seen before include "Furnace, kiln" , "Place for burning" , "A hot place" , "Part of a cooker" , "Small furnace" .)