Significant worker, one having special skills (9)
I believe the answer is:
operative
This clue is a double definition.
'significant' is the first definition.
(I've seen this before)
'worker one having special skills' is the second definition.
(as in intelligence operative)
(Other definitions for operative that I've seen before include "Working (person)" , "Worker in manufacturing" , "Significant" , "Having force - skilled worker" , "secret agent" .)