Never ever green, even vaguely? That's primarily desert (5)
I believe the answer is:
negev
'desert' is the definition.
(Negev is an example)
'never ever green even vaguely? that's primarily' is the wordplay.
'that's primarily' says to take the initial letters.
The first letters of 'never ever green even vaguely' is 'NEGEV'.
(Other definitions for negev that I've seen before include "Israeli desert area abutting Sinai" , "Southern Israeli desert" , "Wilderness" , "Desert region in Israel" , "Semi-desert area" .)