Subject those people start to enjoy (5)
I believe the answer is:
theme
'subject' is the definition.
('theme' can be a synonym of 'subject')
'those people start to enjoy' is the wordplay.
'those people' becomes 'them' (I've seen this before).
'start to' suggests taking the first letters.
The first letter of 'enjoy' is 'e'.
'them'+'e'='THEME'
(Other definitions for theme that I've seen before include "Musical idea; topic" , "[(type of) PARK]" , "Recurring melody" , "Topic, leitmotif" , "Main idea or topic" .)