Is mum making seafood broth with nothing missing? (5,2)
I believe the answer is:
clams up
'is mum' is the definition.
(I've seen this before)
'seafood broth with nothing missing?' is the wordplay.
I cannot really understand how this works, but
'seafood' could be 'clams' (I've seen this in another clue) and 'clams' is found within the answer.
The remaining letters 'up' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'making' is the link.
Can you help me to learn more?
(Other definitions for clams up that I've seen before include "Is mum" , "Refuses to talk" , "abruptly stops talking" .)