Le Pen for instance found in sea (6)
I believe the answer is:
marine
I believe this is a double definition.
'le pen for instance' is the first definition.
(Marine Le Pen)
'found in sea' is the second definition.
(marine means relating to the sea)
(Other definitions for marine that I've seen before include "Soldier associated with a navy" , "Member of the forces" , "Maritime - seagoing soldier" , "Oceanic" , "Sea-soldier" .)