Wager I'd be found in a bathroom item (5)
I believe the answer is:
bidet
'a bathroom item' is the definition.
(I've seen this before)
'wager i'd be found in' is the wordplay.
'wager' becomes 'bet' (synonyms).
'be found in' means one lot of letters goes inside another.
'bet' going around 'id' is 'BIDET'.
(Other definitions for bidet that I've seen before include "Cleaning vessel for privates" , "behind cleaner" , "Bathroom fitting" , "Low basin for washing private parts" , "Where to wash" .)