7 21 racket arranged with Tyneside restaurateurs at its heart (6,3)
I believe the answer is:
dinner set
'tyneside restaurateurs at its heart' is the definition.
I can't judge whether this defines the answer.
'7 21 racket arranged' is the wordplay.
'7 id racket' becomes 'dinner' (I can't justify this - if you can you should give a lot more credence to this answer).
'arranged' becomes 'set' ('set' can be similar in meaning to 'arranged').
'dinner'+'set'='DINNER-SET'
'with' acts as a link.
(Other definitions for dinner set that I've seen before include "might be taken out for a meal" , "Table service" , "Plates etc" , "crockery" , "Collection of plates and dishes" .)