Howl like a horse? (3)
I believe the answer is:
bay
This clue is a double definition.
'howl' is the first definition.
(I've seen this before)
'a horse?' is the second definition.
(I know that bay is a type of horse)
'like' acts as a link.
(Other definitions for bay that I've seen before include "Chestnut" , "Howl" , "Botany, Galway or Tampa" , "Part of sea" , "Curved inlet; tree" .)