Convenient work involving nothing too active, primarily (2,3)
I believe the answer is:
on tap
'convenient' is the definition.
(thesaurus)
'work involving nothing too active primarily' is the wordplay.
'work' becomes 'op' (abbreviation for opus**).
'involving' means one lot of letters goes inside another.
'primarily' says to take the initial letters.
The initial letters of 'nothing too active' is 'nta'.
'op' going around 'nta' is 'ON TAP'.
(Other definitions for on tap that I've seen before include "Readily available" , "where C or H is seen?" , "Ready to be drawn off, like beer" , "handy" , "Where to find a washer" .)