Cruel fact: you need to get rid of tattoo for promotion (8)
I believe the answer is:
sadistic
'cruel' is the definition.
(I've seen this before)
'fact you need to get rid of tattoo for promotion' is the wordplay.
I cannot really understand how this works, but
'promotion' could be 'ad' (short for advert) and 'ad' is located in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for sadistic that I've seen before include "Loving cruelty" , "Cruel and perverted" , "This kind of person enjoys cruelty" , "Enjoying others' pain" , "nasty" .)