Hull market restricts hotel (5)
I believe the answer is:
shell
'hull' is the definition.
(shell is a kind of hull)
'market restricts hotel' is the wordplay.
'market' becomes 'sell' (I've seen this before**).
'restricts' is an insertion indicator.
'hotel' becomes 'h' (phonetic alphabet: alpha, bravo, charlie etc.).
'sell' enclosing 'h' is 'SHELL'.
(Other definitions for shell that I've seen before include "pepper?" , "(Turtle's) carapace" , "Hull" , "Carapace; bombard" , "Protective outer casing" .)