Part of hospitality industry: foolish people in retirement (4)
I believe the answer is:
spas
'part of hospitality industry' is the definition.
'foolish people in retirement' is the wordplay.
'foolish people' becomes 'saps'.
'in retirement' says the letters should be written backwards (retire can mean to go back or backwards).
'saps' back-to-front is 'SPAS'.
(Other definitions for spas that I've seen before include "Health resorts near springs" , "Bath and suchlike" , "Mineral springs" .)