Element to stop change (5)
I believe the answer is:
amend
'change' is the definition.
(amending is a kind of changing)
'element to stop' is the wordplay.
'element' becomes 'am' (Am is an example).
'to stop' becomes 'end' ('end' can be a synonym of 'stop').
'am'+'end'='AMEND'
(Other definitions for amend that I've seen before include "Make small changes to" , "Modify - edit" , "Make small improvements to" , "Make corrections to (eg, document)" , "Corrct error, make a minor aleration" .)