Suit half the hot tub (3)
I believe the answer is:
spa
'hot tub' is the definition.
(I've seen this in another clue)
'suit half' is the wordplay.
'suit' becomes 'spades' (playing card suit).
'half' suggests halving the letters.
'spades' halved is 'SPA'.
'the' is the link.
(Other definitions for spa that I've seen before include "Resort with mineral water spring" , "eg Bath" , "Bath - mineral water spring" , "Health resort near a spring" , "Bath, possibly" .)