It could make stay with British hosts healthy one (9)
I believe the answer is:
whalebone
'it could make stay' is the definition.
(a stay is a corset once made with whalebone)
'with british hosts healthy one' is the wordplay.
'with' becomes 'w' (abbreviation**).
'british' becomes 'b' (abbreviation e.g. in 'BBC').
'hosts' indicates putting letters inside.
'healthy' becomes 'hale' ('hale' can be similar in meaning to 'healthy').
'w'+'b'='wb'
'wb' placed around 'hale' is 'whaleb'.
'whaleb'+'one'='WHALEBONE'
(Other definitions for whalebone that I've seen before include "Spoilt, over-indulged" , "It could make stay" , "Stiffener made from sea beast" , "It was formerly used for corset stays" .)