Chore is transformed into thrilling activity (7)
I believe the answer is:
heroics
'thrilling activity' is the definition.
'heroics' can be an answer for 'activity' (heroics is a kind of activity). I'm not certain of the 'thrilling' bit.
'chore is transformed' is the wordplay.
'transformed' indicates an anagram.
'chore'+'is'='choreis'
'choreis' is an anagram of 'HEROICS'.
'into' acts as a link.
Can you help me to learn more?
(Other definitions for heroics that I've seen before include "Bold and dramatic behaviour" , "Unduly bold behaviour" , "Amazing feats" , "Outstanding performance" , "Brave deeds" .)