Bob carries jug round? Impossible! (2,3,2)
I believe the answer is:
no can do
'impossible' is the definition.
('no can do' can mean something is impossible)
'bob carries jug round?' is the wordplay.
'bob' becomes 'nod'.
'carries' is an insertion indicator (inserted letters carried inside).
'jug' becomes 'can' (both are containers).
'round?' becomes 'o' (round can mean a round object).
'nod' placed around 'can' is 'nocand'.
'nocand'+'o'='NO CAN DO'
(Other definitions for no can do that I've seen before include "off-putting response" , "Nothing manageable" , "Informal expression of refusal" , "Impossible, I'm afraid!" , "That's out of the question!" .)