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 anagramming the letters.
'went' is an anagram of '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" .)