Slow worker at court under silly rule (9)
I believe the answer is:
reluctant
'slow' is the definition.
(I've seen this before)
'worker at court under silly rule' is the wordplay.
'worker' becomes 'ant' (worker is a type of ant).
'at' says to put letters next to each other (I've seen this in other clues).
'court' becomes 'ct' (abbreviation used in road names).
'under' says to put letters next to each other.
'silly' indicates anagramming the letters.
'rule' anagrammed gives 'relu'.
'ant' after 'ct' is 'ctant'.
'ctant' put after 'relu' is 'RELUCTANT'.
(Other definitions for reluctant that I've seen before include "Disinclined to become involved" , "Unwilling to do something" , "Unwilling, disinclined" , "Unwilling, hesitant" , "Loth" .)