Goes down with many a subscription (4)
I believe the answer is:
dips
'goes down' is the definition.
(dipping is a kind of going down)
'with many a subscription' is the wordplay.
'with' means one lot of letters go next to another.
'many' becomes 'D' (Roman numeral for 500).
'a subscription' becomes 'ips' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'd'+'ips' is 'DIPS'.
Can you help me to learn more?
(Other definitions for dips that I've seen before include "Briefly immerses" , "Lowers into liquid" .)