Rubbish in middle of ship picked up (5)
I believe the answer is:
waste
'rubbish' is the definition.
(I know that rubbish can be written as waste)
'middle of ship picked up' is the wordplay.
'middle of ship' becomes 'waist' (I've seen this before).
'picked up' shows a homophone (sound like).
'waist' is a homophone of 'WASTE'.
'in' is the link.
(Other definitions for waste that I've seen before include "Use to no purpose" , "Sweat (anag)" , "Blow - rubbish" , "unused" , "Unwanted material" .)