In safe space, nothing is to tease (4,2)
I believe the answer is:
have on
'is to tease' is the definition.
(to have someone on is to trick or tease them)
'in safe space nothing' is the wordplay.
'in' indicates putting letters inside.
'safe space' becomes 'haven' (a haven is a safe place).
'nothing' becomes 'O' (O resembles 0).
'haven' going around 'o' is 'HAVE ON'.
(Other definitions for have on that I've seen before include "Wear" , "kid" , "Tease" .)