Some burrow in sandbanks (4)
I believe the answer is:
eels
(Other definitions for eels that I've seen before include "Sea snakes among lees" , "Long, fleshy fish" , "Smooth fishes" , "Slender fish" , "eg Conger" .)
I believe the answer is:
eels
(Other definitions for eels that I've seen before include "Sea snakes among lees" , "Long, fleshy fish" , "Smooth fishes" , "Slender fish" , "eg Conger" .)