In Sumatra I need an apprentice... (7)
I believe the answer is:
trainee
'an apprentice' is the definition.
(someone undergoing training)
'in sumatra i need' is the wordplay.
'in' says the answer is hidden in the clue.
'TRAINEE' is hidden in the letters of 'sumatra i need'.
(Other definitions for trainee that I've seen before include "One undergoing instruction" , "One taking instruction" , "As pupil" , "One learning a job" , "A beginner in Aintree" .)