Bath gushing in middle (3,3)
I believe the answer is:
'bath' is the definition.
(I know that hot tub is a type of bath)
'gushing in middle' is the wordplay.
'gushing' becomes 'OTT' (gushing can mean over the top).
'in' is an insertion indicator.
'middle' becomes 'hub' (hub is a kind of middle).
'ott' put within 'hub' is 'HOT TUB'.
(Other definitions for hot tub that I've seen before include "Outdoor bath" , "bubble bath" , "Jacuzzi" , "Spa feature" , "bathing facility" .)