Lacking imagination (10)
'lacking imagination' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for prosaic that I've seen before include "boring!" , "Humdrum" , "Matter-of-fact" , "Dull -- commonplace" , "Hackneyed" .)
(Other definitions for uninspired that I've seen before include "Pedestrian" , "Showing no imagination" , "Unimaginative, dull" , "Boring" .)