Smelly person not starting to mess about (6)
I believe the answer is:
tinker
'to mess about' is the definition.
(I've seen this before)
I cannot understand how the remainder of the clue works.
(Other definitions for tinker that I've seen before include "Make trivial changes" , "Meddle" , "Fiddle with machinery" , "Make trivial adjustments - itinerant tradesman" , "Mender of pots and pans" .)