Grab drink after rest is consumed (4,2)
I believe the answer is:
snap up
'grab' is the definition.
(I know that grab can be written as snap up)
'drink after rest is consumed' is the wordplay.
'drink' becomes 'sup' (to sup is to drink).
'after rest' becomes 'nap' (I've seen this in another clue. I am not sure about the 'after' bit.).
'is consumed' is an insertion indicator.
'sup' going around 'nap' is 'SNAP UP'.
Can you help me to learn more?
(Other definitions for snap up that I've seen before include "Purchase eagerly and quickly" , "Grab eagerly and quickly" , "Buy (a rarity) quickly" , "Unhesitatingly take" , "Snatch" .)