It's wrong to pursue old name (4)
I believe the answer is:
otis
'name' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'it's wrong to pursue old' is the wordplay.
'wrong' is an anagram indicator.
'to pursue' is a charade indicator (letters next to each other).
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'its' anagrammed gives 'tis'.
'tis' after 'o' is 'OTIS'.
Can you help me to learn more?
(Other definitions for otis that I've seen before include "US inventor" , "---- Redding, 1941-67, soul singer" , "Place of worship; side part of head" , "Company providing lifts" , "- - Redding (soul music star)" .)