Ordinary horse - spotted one with teeth (7)
I believe the answer is:
hacksaw
'one with teeth' is the definition.
I can't judge whether this definition defines the answer.
'ordinary horse spotted' is the wordplay.
'ordinary horse' becomes 'hack' (hack is a kind of horse. I am not sure about the 'ordinary' bit.).
'spotted' becomes 'saw' (spot can mean to see).
'hack'+'saw'='HACKSAW'
Can you help me to learn more?
(Other definitions for hacksaw that I've seen before include "Blade in a frame under tension" , "One cuts" , "Metal cutter" , "Toothed tool for cutting metal" , "cutting edge" .)