Pub about to open lovely keg (6)
I believe the answer is:
barrel
'keg' is the definition.
(I've seen this in another clue)
'pub about to open lovely' is the wordplay.
'pub' becomes 'bar' (both are drinking establishments).
'about' becomes 're' ('re' means regarding or about).
'to open' indicates taking the first letters (take the opening letter).
The initial letter of 'lovely' is 'l'.
'bar'+'re'+'l'='BARREL'
(Other definitions for barrel that I've seen before include "Round wooden cask made by cooper" , "Wood vessel; part of horse" , "Cheerful old song: 'Roll out the . . . . . .'" , "Cylinder with metal hoops" , "Beer measure; gun part" .)