English queen favoured stable's latest horse (6)
I believe the answer is:
equine
'horse' is the definition.
(thesaurus)
'english queen favoured stable's latest' is the wordplay.
'english' becomes 'e' (abbreviation).
'queen' becomes 'qu' (**).
'favoured' becomes 'in' (I've seen this in other clues).
'latest' indicates one should take the final letters.
The last letter of 'stable' is 'e'.
'e'+'qu'+'in'+'e'='EQUINE'
(Other definitions for equine that I've seen before include "Horse-like" , "Horsey" , "like knight?" , "Resembling a horse" , "Horsy" .)