Stands high on board ship (6)
I believe the answer is:
stalls
'stands' is the definition.
('stall' can be a synonym of 'stand')
'high on board ship' is the wordplay.
'high' becomes 'tall' ('tall' is associated in meaning with 'high'**).
'on board' means one lot of letters goes inside another.
'ship' becomes 'ss'.
'tall' going inside 'ss' is 'STALLS'.
(Other definitions for stalls that I've seen before include "Most expensive theatre seats" , "Compartments for horses" , "Uses delaying tactics to gain time" , "Plays for time" , "Market stands for the sale of goods" .)