Former President, old hand at work in stoppages (4,5)

'former president' is the definition.
I don't know anything about this answer so I can't judge whether it can be defined by this definition.

'old hand at work in stoppages' is the wordplay.
'old' becomes 'o' (abbreviation).
'at work' indicates anagramming the letters.
'in' means one lot of letters goes inside another.
'stoppages' becomes 'jams' (I am not sure about this - if you are sure you should believe this answer much more).
'o'+'hand'='ohand'
'ohand' is an anagram of 'ohnad'.
'ohnad' placed inside 'jams' is 'JOHN ADAMS'.

Can you help me to learn more?