Here are 10 advanced-level phrasal verbs with their meanings and example sentences. They have more nuanced or idiomatic meanings:

     brush up on

Meaning: To review or refresh one's knowledge of something

Example: I need to brush up on my French before my trip to Paris next month.

     chip in

Meaning: To contribute or help, especially with money or effort

Example: Everyone chipped in to buy the boss a retirement gift.

     drum up

Meaning: To gather or create interest or support

Example: The marketing team is trying to drum up interest for the new product launch.

     fend off

Meaning: To defend against or resist

Example: The company had to fend off multiple takeover attempts from competitors.

     iron out

Meaning: To resolve or settle differences or problems

Example: We need to iron out the details of the contract before signing.

     mull over

Meaning: To think about deeply; to consider at length

Example: I've been mulling over your proposal, and I have a few questions.

     plough through

Meaning: To work through something difficult or tedious with determination

Example: I had to plough through hundreds of pages of legal documents to find the relevant information.

     sift through

Meaning: To examine carefully to find something

Example: The detectives had to sift through mountains of evidence to solve the case.

     touch upon

Meaning: To mention briefly or lightly

Example: The speaker touched upon several controversial topics during her presentation.

     zero in on

Meaning: To focus intently on; to target precisely

Example: The researchers are zeroing in on a potential cure for the disease.