Stops mess developing, with time (5)
I believe the answer is:
stems
'stops' is the definition.
(stemming is a kind of stopping)
'mess developing with time' is the wordplay.
'developing with' indicates an anagram (letters developed into a new form).
'time' becomes 't' (abbreviation).
'mess' anagrammed with 't' makes 'STEMS'.
(Other definitions for stems that I've seen before include "Stops" , "springs" , "Slender upright parts, flowers or glasses" , "Structures that support plants" , "things growing?" .)