### Clue: Insect repellent affected some horses (7)
### Answer: CAMPHOR 
 ### Explanation: Definition: Insect repellent
  CAMP(descriptive of affected behaviour, that which is artificial, vulgar and put-on.  Is it PC to say also descriptive of homosexuals, as given in Collins?) HOR(some,the first 3 letters of "horses")
Defn:  A tough gummy aromatic compound derived from the wood and bark of the camphor tree, can be used as an insect repellent.  A camphorwood chest is great for keeping clothes safe from cloth-eating moths and other bugs.