Points to large and small fish (4)
I believe the answer is:
eels
'fish' is the definition.
(eel is a type of fish)
'points to large and small' is the wordplay.
'points' becomes 'ee' (an abbreviation for a compass point written twice).
'to large' becomes 'L' (eg in clothes sizes).
'and' means one lot of letters go next to another.
'small' becomes 's' (abbreviation - e.g. clothes size).
'ee'+'l'+'s'='EELS'
(Other definitions for eels that I've seen before include "Slippery types" , "Slender fish" , "Conger --; jellied --" , "They have long bodies and very small fins" , "Slithery fish" .)