Inflexible part of ship? (5)
I believe the answer is:
stern
I believe this is a triple definition!
'inflexible' is the first definition.
('stern' can be similar in meaning to 'inflexible')
'part' is the second definition.
(stern is a kind of part)
'of' acts as a link.
'ship?' is the third definition.
(thesaurus)
(Other definitions for stern that I've seen before include "Grim; severe" , "Rear of a vessel" , "Severe and unremitting: area of a ship" , "Looking severe" , "Severe, forbidding" .)