Beyond delta, soil shortage (6)
I believe the answer is:
dearth
'shortage' is the definition.
(dearth can mean a shortage or lack)
'beyond delta soil' is the wordplay.
'beyond' is a charade indicator (letters next to each other).
'delta' becomes 'd' (phonetic alphabet: alpha, bravo, charlie etc.).
'soil' becomes 'earth' (synonyms).
'd'+'earth' is 'DEARTH'.
(Other definitions for dearth that I've seen before include "Scarcity, paucity" , "Scarcity of thread" , "poverty" , "Scarcity - lack" , "want" .)