Silver parts we carry on (4)
I believe the answer is:
wage
'carry on' is the definition.
(as in waging war)
'silver parts we' is the wordplay.
'silver' becomes 'Ag' (Ag is the chemical symbol for silver).
'parts' means one lot of letters goes inside another (inserted letters separate or part others).
'ag' going within 'we' is 'WAGE'.
(Other definitions for wage that I've seen before include "conduct" , "Engage in (war?)" , "Regular payment for work" , "Money earned" , "Pursue" .)