Asks the sea to recede and the sand to swirl (7)
I believe the answer is:
demands
'asks' is the definition.
('demand' can be a synonym of 'ask')
'sea to recede and the sand to swirl' is the wordplay.
'sea' becomes 'med' (abbreviation of Mediterranean).
'to recede' says the letters should be written in reverse.
'and' means one lot of letters go next to another.
'to swirl' indicates anagramming the letters (I've seen 'swirling' mean this).
'med' in reverse letter order is 'dem'.
'sand' anagrammed gives 'ands'.
'dem'+'ands'='DEMANDS'
'the' acts as a link.
(Other definitions for demands that I've seen before include "Requires" , "Insistent requests" , "Requests forcefully" , "Insists upon" , "Asks peremptorily" .)