America supplied desert plant (5)
I believe the answer is:
agave
'desert plant' is the definition.
(agave is a kind of desert plant)
'america supplied' is the wordplay.
'america' becomes 'a' (common abbreviation eg in USA).
'supplied' becomes 'gave' (giving is a kind of supplying).
'a'+'gave'='AGAVE'
(Other definitions for agave that I've seen before include "source of tequila" , "Succulent; daughter of Cadmus" , "Tropical plant" , "Plant, source of sisal" , "native growing up in tropical America" .)