Announced cover charge for water (7)
I believe the answer is:
hydrate
'water' is the definition.
(I've seen this before)
'announced cover charge' is the wordplay.
I cannot really understand how this works, but
'charge' could be 'rate' (rate is a kind of charge) and 'rate' is found in the answer.
This explanation may well be incorrect...
'for' is the link.
Can you help me to learn more?
(Other definitions for hydrate that I've seen before include "Give water" , "Cause (something) to absorb water" , "Moisturise" , "compound" , "Supply liquid" .)