Young newt (3)
I believe the answer is:
eft
'young newt' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for eft that I've seen before include "Swimmer with feeble legs" , "Little creature" , "Juvenile twenty-three Ac; rhymes with sinister" , "Newt (archaic)" , "Kind of newt found in clefts" .)