A panel on a ship? (6)
I believe the answer is:
aboard
'on a ship?' is the definition.
(I've seen this before)
'a panel' is the wordplay.
'panel' becomes 'board' (synonyms).
'a'+'board'='ABOARD'
(Other definitions for aboard that I've seen before include "Part of the group" , "On vessel or vehicle" , "A poet penning nothing on vessel" , "On an aircraft" , "on a plane, perhaps" .)