Swell making one sick in front of ship (6)
I believe the answer is:
billow
'swell' is the definition.
(thesaurus)
'one sick in front of ship' is the wordplay.
'one sick' becomes 'ill' (I've seen this before).
'in' means one lot of letters goes inside another.
'front of ship' becomes 'bow' (I've seen this before).
'ill' put inside 'bow' is 'BILLOW'.
'making' acts as a link.
(Other definitions for billow that I've seen before include "Swell out (as a sail)" , "Wave; upward flow" , "A great wave or swell" , "Swell out in the wind" , "Surge" .)