Lad in tights introduced fetish to Navy (5)
I believe the answer is:
robin
'lad in tights' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'introduced fetish to navy' is the wordplay.
I cannot really understand how this works, but
'fetish' could be 'obi' (fetish or charm in obi or obeah witchcraft) and 'obi' is found in the answer.
'navy' could be 'rn' (abbreviation for Royal Navy) and 'rn' is found in the leftover letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for robin that I've seen before include "Batman's helper" , "Famous outlaw" , "Small brown thrush" , "Red and brown songbird" , "Red-breasted Christmas card bird" .)