Went off eft (4)
I believe the answer is:
newt
'eft' is the definition.
(I've seen this before)
'went off' is the wordplay.
'off' indicates an anagram.
'went' with letters rearranged gives 'NEWT'.
(Other definitions for newt that I've seen before include "Garden-pond amphibian" , "Small, lizard-like amphibian" , "found in pond!" , "Went to find amphibian" , "Medical worker" .)