Be of one mind about English silver, first (5)
I believe the answer is:
agree
'be of one mind' is the definition.
(I've seen this before)
'about english silver first' is the wordplay.
'about' becomes 're' (regarding**).
'english' becomes 'e' (abbreviation).
'silver' becomes 'ag' (Ag is the chemical symbol for silver).
'first' says to put letters next to each other.
're'+'e'='ree'
'ree' after 'ag' is 'AGREE'.
(Other definitions for agree that I've seen before include "Accord, match" , "Go along with" , "Accept" , "Be of one mind" , "suit" .)