See splash at sea without form (9)
I believe the answer is:
shapeless
'without form' is the definition.
('form' can be 'shape' (synonyms) so maybe 'without form' can be ''shapeless')
'see splash at sea' is the wordplay.
'at sea' is an anagram indicator.
'see'+'splash'='seesplash'
'seesplash' anagrammed gives 'SHAPELESS'.
(Other definitions for shapeless that I've seen before include "Without definite form" , "Amorphous" , "unstructured" , "unattractive to look at?" , "Lacking definite form" .)