Trials of European, for example, on board steamship (6)
I believe the answer is:
essays
'trials' is the definition.
(I've seen this in another clue)
'european for example on board steamship' is the wordplay.
'european' becomes 'e' (abbreviation e.g. EU).
'for example' becomes 'say' ('say' can be used to introduce an example).
'on board' indicates putting letters inside (inserted letters are taken on board).
'steamship' becomes 'ss' (nautical abbreviation).
'say' inserted within 'ss' is 'ssays'.
'e'+'ssays'='ESSAYS'
'of' acts as a link.
(Other definitions for essays that I've seen before include "Short pieces of writing as for homework" , "Tries for theses?" , "Attempts, writing" , "Written works" , "Disquisitions" .)