Surely not clerical assistants for the rank and file! (7,11)

'surely not clerical assistants for' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.

'rank and file' is the wordplay.
I cannot quite understand how this works, but
'rank' could be 'private' (I've seen this before) and 'private' is located in the answer.
The remaining letters 'secretaries' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...

'the' is the link.

Can you help me to learn more?