Basic sandwiches providing livelihood (5,3,6)
I believe the answer is:
bread and butter
'basic' is the definition.
(I've seen this before)
'sandwiches providing livelihood' is the wordplay.
I cannot really understand how this works, but
'livelihood' could be 'bread' (I've seen this in another clue) and 'bread' is found within the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for bread and butter that I've seen before include "Means of support" , "basic course" , "Subsistence" , "earned?" , "sandwiches?" .)