You, on drop of plonk, went out refreshed (7)
I believe the answer is:
updated
'refreshed' is the definition.
'you on drop of plonk went out' is the wordplay.
'you' becomes 'u' (commonly used in online communication).
'on' says to put letters next to each other.
'drop of' says to take the initial letters.
'went out' becomes 'dated' (dating is a kind of going out).
The initial letter of 'plonk' is 'p'.
'u'+'p'+'dated'='UPDATED'
(Other definitions for updated that I've seen before include "Dude apt to be made current" , "Modernised" , "revised" , "Made something more modern" , "Brought to current status" .)