Moderates shouldn't lose them (7)
I believe the answer is:
tempers
'moderates' is the definition.
(I know this)
'shouldn't lose them' is the wordplay.
I cannot really see how this works, but
'them' could be 'em' (abbreviation) and 'em' is located in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for tempers that I've seen before include "Hardens steel" , "Hardens metal by heating and cooling" .)