Amphibian departed, abandoning lake (3)
I believe the answer is:
eft
'amphibian' is the definition.
(eft is a kind of amphibian)
'departed abandoning lake' is the wordplay.
'departed' becomes 'left' (to leave is to depart).
'abandoning' suggests deleting specific letters.
'lake' becomes 'L' (geographical abbreviation).
'left' with 'l' taken away is 'EFT'.
(Other definitions for eft that I've seen before include "Little creature" , "Juvenile newt" , "Slimy creature" , "Newt (archaic)" , "Young newt" .)