Observed to have a row of sharp teeth (3)
I believe the answer is:
saw
'observed' is the definition.
(I've seen this before)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for saw that I've seen before include "Grasped" , "Viewed; maxim" , "Carpentry tool" , "Old saying for wood cutter" , "See 23" .)