Fuddy-duddy (5-2-3-3)
I believe the answer is:
stick-in-the-mud
'fuddy-duddy' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for stick-in-the-mud that I've seen before include "One who won't get moving" , "Old fashioned" , "Completely unenterprising person" , "Fogeyish" , "Staid, unimaginative person" .)