What's added to the pot, brewing tea around noon (4)
I believe the answer is:
'what's added to the pot' is the definition.
(as in the ante in poker)
'brewing tea around noon' is the wordplay.
'brewing' indicates anagramming the letters.
'around' means one lot of letters goes inside another.
'noon' becomes 'n' (abbreviation for noon).
'tea' with letters rearranged gives 'ate'.
'ate' enclosing 'n' is 'ANTE'.
(Other definitions for ante that I've seen before include "early payment" , "Stake; before (Lat.)" , "Advance stake" , "Fixed stake" , "'Behind, before (4)'" .)