He spoke at sea for each one who's flogged a lot? (10)
I believe the answer is:
shopkeeper
'one who's flogged a lot?' is the definition.
(someone who sells or flogs things)
'he spoke at sea for each' is the wordplay.
'at sea' indicates an anagram.
'for each' becomes 'per' (I've seen this before).
'he'+'spoke'='hespoke'
'hespoke' with letters rearranged gives 'shopkee'.
'shopkee'+'per'='SHOPKEEPER'
(Other definitions for shopkeeper that I've seen before include "perhaps Napoleon's man in England?" , "Counter-agent" , "E.g. newsagent" , "Tradesperson" .)