Flat shortage with curious result (10)
I believe the answer is:
lacklustre
'flat' is the definition.
(thesaurus)
'shortage with curious result' is the wordplay.
'shortage' becomes 'lack' (I've seen this before).
'with' is a charade indicator (letters next to each other).
'curious' is an anagram indicator.
'result' anagrammed gives 'lustre'.
'lack'+'lustre'='LACKLUSTRE'
(Other definitions for lacklustre that I've seen before include "Unimaginative" , "Without vitality" , "Prosaic" , "sluggish performance" , "Drab" .)