Starts eating with Teresa from ringside seat (4,2)
I believe the answer is:
digs in
'starts eating' is the definition.
Although both the answer and definition are verbs in their -s form, I don't see how one could define the other.
'teresa from ringside seat' is the wordplay.
I cannot quite see how this works, but
'from' could be 'in' (I've seen this in other clues) and 'in' is found within the answer.
The remaining letters 'digs' is a valid word which might be clued in a way I don't understand.
This may be the basis of clue (or it may be nonsense).
'with' acts as a link.
Can you help me to learn more?
(Another definition for digs in that I've seen is " start[S] to eat heartily".)