What to keep when out of control (4)
I believe the answer is:
cool
'control' is the definition.
(thesaurus)
'what to keep when out of' is the wordplay.
I cannot really understand how this works, but
'of' could be 'o' and 'o' is found in the answer.
The remaining letters 'col' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for cool that I've seen before include "Relaxed; not warm" , "Unemotional; excellent" , "Rain heavily (colloq.)" , "Calm and unemotional" , "Moderate" .)