Don't take part in operation against ticket seller (3,3)
I believe the answer is:
opt out
'don't take part in' is the definition.
I can't tell whether this defines the answer.
'operation against ticket seller' is the wordplay.
'operation' becomes 'op'.
'against' says to put letters next to each other.
'ticket seller' becomes 'tout' (as in a ticket tout).
'op'+'tout'='OPT-OUT'
Can you help me to learn more?
(Other definitions for opt out that I've seen before include "Choose not to do something" , "Choose not to participate" , "Decide not to participate" , "Decline to participate" , "Decide to withdraw" .)