This ***other walkthrough by Zurreen Zubairie***
Look at the pool, just left of the basket-weaver. Note the dark brown speck on a water-lily pad closest to the edge of the pool in front of you. Click on the gear icon appearing on that pad to learn that there is something shining on it. Use the Grappling Hook from your inventory on that shiny object on the lily pad, to bring the pad closer to you. [Note: Be sure to place the triangular tip (i.e., "<") of your cursor on the lily pad, completely covering the brown object on the pad, in order to succeed in moving the lily pad in the very first try.] A cutscene follows. Pick up the Gouge from the lily pad.
The ***walkthrough by Malcolm Schmidt***
Now go back to the worker, and while facing him, pan to your left to see something shining on one of the lily pads in the pool. Use the grappling hook to pull the lily pad closer and take the gouge.
Does that help? I really don't remember this puzzle at all. It sounds like you have to do something to trigger the availability of the lily pad. Make sure you're standing in the right place and aiming for the right lily pad. If none of this helps, you might be able to get more tips in the Hints section.