Bath hot, dealer lying back, maybe (7)
I believe the answer is:
perhaps
'maybe' is the definition.
(synonyms)
'bath hot dealer lying back' is the wordplay.
'bath' becomes 'spa' (I've seen this before).
'hot' becomes 'h' (abbreviation eg on taps).
'dealer' becomes 'rep'.
'lying back' shows that the letters should be reversed in order.
'spa'+'h'+'rep'='spahrep'
'spahrep' back-to-front is 'PERHAPS'.
(Other definitions for perhaps that I've seen before include "Could be, maybe" , "It may be" , "Conceivably" , "Not necessarily" , "Quite possibly" .)