Party concentrated, needing a lot of workers (6-9)
I believe the answer is:
labour-intensive
'a lot of workers' is the definition.
I know nothing about this answer so I can't judge whether it can be defined by this definition.
'party concentrated' is the wordplay.
'party' becomes 'labour' (Labour Party is an example).
'concentrated' becomes 'intensive' (synonyms).
'labour'+'intensive'='LABOUR-INTENSIVE'
'needing' acts as a link.
Can you help me to learn more?
(Another definition for labour-intensive that I've seen is " Involving much work".)