Mentioned that place of those people (5)
I believe the answer is:
their
'of those people' is the definition.
(I've seen this before)
'mentioned that place' is the wordplay.
'mentioned' indicates a 'sounds like' (homophone) clue.
'that place' becomes 'there' (I've seen this before).
'there' is a homophone of 'THEIR'.
(Other definitions for their that I've seen before include "Belonging to him (perhaps wrongly)" , "belonging to an individual" , "Relating to them" , "Some would say his (or her)" , "Those people's" .)