Aromatic plant: partner to pop one in cold beer! (8)
I believe the answer is:
camomile
'aromatic plant' is the definition.
(I've seen this in another clue)
'pop one in cold beer' is the wordplay.
'pop' becomes 'mom' (I can't justify this - if you can you should believe this answer much more).
'one' becomes 'i' (Roman numeral).
'in' means one lot of letters goes inside another.
'cold' becomes 'c' (eg on taps).
'beer' becomes 'ale' (type of beer).
'mom'+'i'='momi'
'c'+'ale'='cale'
'momi' put inside 'cale' is 'CAMOMILE'.
'partner to' is the link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for camomile that I've seen before include "Wild flower used medicinally and for tea" , "Milo came with a medicinal plant" , "Fragrant plant" , "Aromatic plant used in tea" , "Sweet-smelling plant used to make medicine and lotion" .)