Tablet poisoning animal, one runs home (7)
I believe the answer is:
aspirin
'tablet' is the definition.
(tablet of aspirin medication)
'animal one runs home' is the wordplay.
'animal' becomes 'asp' (I can't explain this - if you can you should believe this answer much more).
'one' becomes 'i' (Roman numeral).
'runs' becomes 'r' (cricket abbreviation).
'home' becomes 'in' ('he's home' can mean 'he's in').
'asp'+'i'+'r'+'in'='ASPIRIN'
'poisoning' acts as a link.
I am not very happy about this link. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for aspirin that I've seen before include "Headache pill" , "Pain-relieving tablet" , "Anti-inflammatory analgesic" , "Mild pain-killing drug" , "Synthetic analgesic" .)