Remain a while, having nothing nasty to deal with (4,2)
I believe the answer is:
stay on
'remain a while' is the definition.
'nothing nasty to deal with' is the wordplay.
'nothing' becomes 'o' (looks like zero - 0).
'to deal with' indicates anagramming the letters (deal with can mean to organise or sort out).
'o'+'nasty'='onasty'
'onasty' is an anagram of 'STAY ON'.
'having' is the link.
(Other definitions for stay on that I've seen before include "stick" , "Remain after others have left" , "Remain after normal time" , "Remain behind" .)