Get it all from Will, as firm memo about teachers is fairly phoney (4,4,5)

'get' is the definition.
I don't know anything about this answer so I cannot tell whether this works.

'it all from will as firm memo about teachers is fairly phoney' is the wordplay.
I cannot really understand how this works, but
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is located in the answer.
'from' could be 'in' (I've seen this in other clues) and 'in' is located in the answer.
'firm' could be 'co' (a firm is a company) and 'co' is found in the answer.
an anagram of 'memo' is 'meom' which is located in the left over letters.
'about' could be 'on' (as in a book 'on' a certain topic) and 'on' is found within the answer.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?