Minister’s secret token of bargain with God (4,5,4)
I believe the answer is:
lord privy seal
'minister's' is the definition.
(Lord Privy Seal is an example)
'secret token of bargain with god' is the wordplay.
'secret' becomes 'privy' (synonyms).
'token of bargain' becomes 'seal' (as in sealing a bargain).
'with' says to put letters next to each other.
'god' becomes 'lord' (the Lord means God).
'privy'+'seal'='privyseal'
'privyseal' put after 'lord' is 'LORD PRIVY SEAL'.
(Other definitions for lord privy seal that I've seen before include "Senior minister without portfolio, usually Leader of the House of Commons or Lords" , "high official" , "minister's office" , "Cabinet member" , "UK cabinet minister without specific departmental duties" .)