Her poem on change may be arousing for others (9)
I believe the answer is:
pheromone
'may be arousing for others' is the definition.
(pheromones may arouse people)
'her poem on change' is the wordplay.
'change' indicates an anagram.
'her'+'poem'+'on'='herpoemon'
'herpoemon' anagrammed gives 'PHEROMONE'.
(Other definitions for pheromone that I've seen before include "Chemical signal between organisms" , "What attracts" , "Chemical attractor" , "Substance secreted that affects others of same species" , "Chemical affecting behaviour" .)