Try it on, every so often, using half of the jars for wine (5)
I believe the answer is:
rioja
'for wine' is the definition.
(Rioja is an example)
'try it on every so often using half of the jars' is the wordplay.
'every so often' means one should take alternating letters.
'using' means one lot of letters go next to another.
'half of' means to take half the letters.
'try'+'it'+'on'='tryiton'
The alternating letters of 'tryiton' are 'rio'.
'jars' halved is 'ja'.
'rio'+'ja'='RIOJA'
(Other definitions for rioja that I've seen before include "Wine from northern Spain" , "Popular Spanish wine" , "Spanish drink" , "it comes from grapevine" , "kind of red" .)