It stands upright in pots, possibly (4)
I believe the answer is:
post
'it stands upright' is the definition.
The definition suggests a singular noun which matches the answer.
'pots possibly' is the wordplay.
'possibly' indicates an anagram.
'pots' is an anagram of 'POST'.
'in' acts as a link.
Can you help me to learn more?
(Other definitions for post that I've seen before include "Stake; appointment" , "Maybe letters" , "Member < to comment on website" , "a placement: it's > part of one's goal" , "Spot the mail" .)