Infusion all there is after this, oddly (6)
I believe the answer is:
tisane
'infusion' is the definition.
(I've seen this before)
'all there is after this oddly' is the wordplay.
'all there' becomes 'sane' ('not all there' can mean insane).
'is after' means one lot of letters go next to another.
'oddly' indicates alternate letters.
The alternate letters of 'this' are 'ti'.
'sane' put after 'ti' is 'TISANE'.
(Other definitions for tisane that I've seen before include "Infusion (eg of herbs or flowers)" , "brew" , "Infusion of e.g. dried or fresh flowers or leaves" , "Herb tea" , "relaxing drink" .)