Horse no one backed after delay (8)
I believe the answer is:
stallion
'horse' is the definition.
(thesaurus)
'no one backed after delay' is the wordplay.
'one' becomes 'i' (Roman numeral).
'backed' says the letters should be written backwards.
'after' is a charade indicator (letters next to each other).
'delay' becomes 'stall' (stalling is a kind of delaying).
'no'+'i'='noi'
'noi' backwards is 'ion'.
'ion' after 'stall' is 'STALLION'.
(Other definitions for stallion that I've seen before include "Stud" , "Male steed" , "Male horse lost in atolls" , "Male horse kept for breeding" , "Uncastrated adult male horse" .)