Sentence:  To <WSD>lip-lock</WSD> a fish, curl your index and middle finger, then gently slide those two fingers under the gill cover and forward toward the fish's nose, applying slight outward pressure with your fingertips until your fingers stop just under the fish's jaw. 
Meaning of the word marked with <WSD> tags:  To hook a fish by inserting a curled finger under the gill cover and extending it to the fish's jaw.