Variety of citrus fruit, not round (5)
I believe the answer is:
range
'variety' is the definition.
(I've seen this before)
'citrus fruit not round' is the wordplay.
'citrus fruit' becomes 'orange' (orange is a kind of citrus fruit).
'not' suggests deleting specific letters.
'round' becomes 'o' (round can mean a round object).
'orange' with 'o' taken out is 'RANGE'.
'of' acts as a link.
(Other definitions for range that I've seen before include "area for stock" , "testing ground" , "Selection" , "Tract of grassy land for livestock" , "Andes or Rockies, perhaps?" .)