A timid, admin clerk reluctantly chooses to be the only stable friend of an erratic, homeless woman she had idolised back when they were School Captain.

Untying the knot and fitting this into the suggested logline?template, you'd come up with something like :

When an erratic, homeless woman?turns out to be the old School Captain she idolised,?a timid, admin clerk must become the tower of strength the woman needs.

This idea seems promising but is a little thin on content.

A few good questions to ask yourself:
--What does the main character want? (This can illuminate why she's reluctant.)
--What's in her way? (this is a great method for hooking readers.)
--How can I give the the logline as much momentum as possible?

From the logling, it's not really clear where the story is going. Consider: "When a timid admin clerk suddenly becomes the only stable friend of an erratic homeless person, she unravels the haunting story of how her high-school idol fell from grace."

This is a scenario, what is a character goal? That would be a story. Being a friend is a noble thing but is demonstrated by action. These actions would be the story which is the goal.

Hope this helps.