Contemplation of past events cost RTÉ rep, badly (10)
I believe the answer is:
retrospect
'contemplation of past events' is the definition.
'retrospect' can be an answer for 'contemplation' (retrospect is a kind of contemplation). I am not sure about the 'of past events' bit.
'cost rte rep badly' is the wordplay.
'badly' indicates anagramming the letters (letters in the wrong order).
'cost'+'rte'+'rep'='costrterep'
'costrterep' anagrammed gives 'RETROSPECT'.
Can you help me to learn more?
(Other definitions for retrospect that I've seen before include "Contemplation of the past" , "Survey of past events" , "Hindsight" , "Look at history" , "A backward view" .)