Solution Victor dropped in Channel at Cowes? (7)
I believe the answer is:
solvent
'solution' is the definition.
'victor dropped in channel at cowes?' is the wordplay.
'victor' becomes 'v' (phonetic alphabet: alpha, bravo, charlie etc.).
'dropped in' is an insertion indicator.
'channel at cowes?' becomes 'solent' (section of the English Channel).
'v' inserted into 'solent' is 'SOLVENT'.
(Other definitions for solvent that I've seen before include "afloat" , "Capable of paying all debts" , "of tradable status?" , "not on the rocks" , "Dissolving liquid" .)