Fish sailor lifted on ship (4)
I believe the answer is:
bass
'fish' is the definition.
(I've seen this before)
'sailor lifted on ship' is the wordplay.
'sailor' becomes 'ab' (abbreviation for able seaman**).
'lifted' shows that the letters should be reversed in order (going up in down clue).
'on' says to put letters next to each other.
'ship' becomes 'ss'.
'ab' reversed gives 'ba'.
'ba'+'ss'='BASS'
(Other definitions for bass that I've seen before include "Big percussion instrument" , "Variety of sea and freshwater perch" , "Very low - perch" , "deep in the sound" , "Low singer" .)