Unimaginative professionals needing ace in charge (7)
I believe the answer is:
prosaic
'unimaginative' is the definition.
(I've seen this in another clue)
'professionals needing ace in charge' is the wordplay.
'professionals' becomes 'pros' ('pro' can be a synonym of 'professional').
'needing' means one lot of letters go next to another.
'ace' becomes 'a' (abbreviation).
'in charge' becomes 'ic' (abbreviation for 'in charge').
'pros'+'a'+'ic'='PROSAIC'
(Other definitions for prosaic that I've seen before include "Dull (writing)" , "Humdrum" , "Poetry would not be so" , "Lacking originality" , "Mundane" .)