Crew of a freighter? (5)
I believe the answer is:
eight
'crew' is the definition.
(I've seen this before)
'of a freighter?' is the wordplay.
'of' says the answer is hidden in the clue.
'EIGHT' is hidden in the letters of 'freighter'.
(Other definitions for eight that I've seen before include "Number of the April rainers" , "Cardinal number" , "Half a quarter" , "Cube of two" , "Crew of racing shell" .)