Charged particle installing resistance in metal (4)
I believe the answer is:
iron
'metal' is the definition.
(iron is a metal)
'charged particle installing resistance' is the wordplay.
'charged particle' becomes 'ion' (I've seen this before).
'installing' means one lot of letters goes inside another (inserted letters are installed).
'resistance' becomes 'r' (electronics abbreviation).
'ion' going around 'r' is 'IRON'.
'in' is the link.
(Other definitions for iron that I've seen before include "Wellington was known as the .... Duke" , "Hard metal" , "great strength" , "Smooth (clothes)" , "See 14" .)