It's old taking balanced infusions (7)
I believe the answer is:
tisanes
'infusions' is the definition.
(I've seen this before)
'it's old taking balanced' is the wordplay.
'it's old' becomes 'tis' (historical version of 'it is').
'taking' means one lot of letters goes inside another.
'balanced' becomes 'sane'.
'tis' placed around 'sane' is 'TISANES'.
(Other definitions for tisanes that I've seen before include "More than one hot drink" , "Herb teas" , "health drinks?" , "herbal teas" , "infusions" .)