Control decay around one that’s spread uncontrolled (3,4)
I believe the answer is:
run riot
'spread uncontrolled' is the definition.
I know nothing about this answer so I cannot tell whether it can be defined by this definition.
'control decay around one' is the wordplay.
'control' becomes 'run' (I've seen this before).
'decay' becomes 'rot' (rot can mean to decay).
'around' is an insertion indicator.
'one' becomes 'i' (Roman numeral).
'rot' enclosing 'i' is 'riot'.
'run'+'riot'='RUN RIOT'
'that's' is the link.
Can you help me to learn more?
(Other definitions for run riot that I've seen before include "Lose control" , "Behave in uncontrolled way as mob might" , "Go wild" , "Go on the rampage" , "Go berserk" .)