The maps I prepared for a fellow sailor (8)
I believe the answer is:
shipmate
'a fellow sailor' is the definition.
(I've seen this before)
'the maps i prepared' is the wordplay.
'prepared' is an anagram indicator.
'the'+'maps'+'i'='themapsi'
'themapsi' is an anagram of 'SHIPMATE'.
'for' acts as a link.
(Other definitions for shipmate that I've seen before include "Sailor on board, a real pal" , "Colleague on board" , "Fellow crew member" , "Fellow seaman" , "Fellow sailor" .)