Best dry toes at sea (7)
I believe the answer is:
destroy
'best' is the definition.
(thesaurus)
'dry toes at sea' is the wordplay.
'at sea' is an anagram indicator.
'dry'+'toes'='drytoes'
'drytoes' is an anagram of 'DESTROY'.
(Other definitions for destroy that I've seen before include "Ruin, put an end to" , "Ruin; pull down" , "Ruin or defeat roundly" , "put to death" , "Kill; ruin" .)