Unimaginative drunk left after considerable time (7)
I believe the answer is:
literal
'unimaginative' is the definition.
(I've seen this before)
'drunk left after considerable time' is the wordplay.
'drunk' becomes 'lit' (I've seen this in another clue).
'left' becomes 'l' (common abbreviation).
'after' says to put letters next to each other.
'considerable time' becomes 'era' (long period of time).
'l' put after 'era' is 'eral'.
'lit'+'eral'='LITERAL'
(Other definitions for literal that I've seen before include "Without exaggeration or embellishment" , "A tiller (anag.)" , "Not figurative" , "primary sense" , "typographical error" .)