The most common and most likely answer to this crossword clue is the 11 letter word AFFECTIVITY
I've seen this crossword clue in The Times
A
F
F
E
C
T
I
V
I
T
Y
Buddy explains!
The straight part
We know that "Power to arouse emotion" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case power to arouse emotion = affectivity.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.