roil
Churn
If I'm thinking correctly, BELT is a four letter word, and it holds up your pants :)
Clog
bind
It is the word used to describe the noise made by propellers as they churn up water as they revolve.
re-up?
Make a word out of the letters add up the letter scores for a total word and add all four.
I think the term may be "re-up"
Churn
A quay is a platform built parallel to the shore where ships can tie up to. A pier is another four letter word where a ship can dock.
NOON
It contractS and relaxes to churn the food and mix it with the bile and other digestive enzymes.