See the last two large fish (3)
I believe the answer is:
eel
'fish' is the definition.
(eel is a type of fish)
'see the last two large' is the wordplay.
'last' indicates one should take the final letters.
'two' shows that letters should be duplicated.
'large' becomes 'L' (eg in clothes sizes).
The last letter of 'the' is 'e'.
'e' duplicated is 'ee'.
'ee'+'l'='EEL'
(Other definitions for eel that I've seen before include "Wriggly fish" , "Large elver" , "Creature like conger or moray" , "Long smooth fish" , "Slippery character" .)