Shortage of diamonds on ground (6)
I believe the answer is:
dearth
'shortage' is the definition.
(dearth can mean a shortage or lack)
'diamonds on ground' is the wordplay.
'diamonds' becomes 'd' (abbreviation for the card suit diamonds).
'on' says to put letters next to each other (in a down clue, letters appear on others).
'ground' becomes 'earth' (synonyms).
'd'+'earth'='DEARTH'
'of' is the link.
(Other definitions for dearth that I've seen before include "Shortage, paucity" , "Scarcity of thread" , "want" , "Scarcity, paucity" , "Shortage, lack" .)