Is first to go through a sex change (6)
I believe the answer is:
exists
'is' is the definition.
The answer and definition can be both to do with fundamental existence as well as being verbs in their -s form.
Maybe there's a link between them I don't understand?
'first to go through a sex change' is the wordplay.
I cannot quite see how this works, but
'first' could be 'ist' and 'ist' is located in the answer.
an anagram of 'sex' is 'exs' which is present in the left over letters.
No letters remain.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for exists that I've seen before include "Is extant" , "Has objective reality" , "Lives" , "Has life" , "Is present in the universe" .)