Talk about having field event on Sunday (7)
I believe the answer is:
discuss
'talk about' is the definition.
(discussing is a kind of talking about)
'field event on sunday' is the wordplay.
'field event' becomes 'discus' (discus is a kind of field event).
'on' means one lot of letters go next to another.
'sunday' becomes 's'.
'discus'+'s'='DISCUSS'
'having' is the link.
(Other definitions for discuss that I've seen before include "Argue" , "Settle" , "Verbally T [TREAT]" , "Debate" , "Talk about (something)" .)