Turn up for small drinks (4)
I believe the answer is:
nips
'drinks' is the definition.
(miniature drink bottles)
'turn up for small' is the wordplay.
'turn' becomes 'pin' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'up' says the letters should be written in reverse (in down clue: letters go upwards).
'for' says to put letters next to each other.
'small' becomes 's' (abbreviation - e.g. clothes size).
'pin' in reverse letter order is 'nip'.
'nip'+'s'='NIPS'
Can you help me to learn more?
(Other definitions for nips that I've seen before include "Takes" , "Tots" , "Pinches - in the bud?" , "Pinches as crab does" , "Pinches - shots" .)