Game personnel in industrial heartland (4)
I believe the answer is:
ruhr
'industrial heartland' is the definition.
(industrial heartland of Germany)
'game personnel' is the wordplay.
'game' becomes 'RU' (rugby union).
'personnel' becomes 'HR' (Human Resources).
'ru'+'hr'='RUHR'
'in' acts as a link.
(Other definitions for ruhr that I've seen before include "German industrial zone, river" , "German industrial area" , "Major industrial region of north-west Germany" , "German industrial region" , "German river flowing into the Rhine" .)