Check front of ship (4)
I believe the answer is:
stem
This clue is a triple definition!
'check' is the first definition.
(both can mean to control or stop)
'front' is the second definition.
(stem is a kind of front)
'of' acts as a link.
'ship' is the third definition.
(thesaurus)
(Other definitions for stem that I've seen before include "part of pipe" , "Thwart; support" , "Halt flow" , "Type of cell" , "Check - part of a plant" .)