A lot to drink as engineers tramp over a mile (8)
I believe the answer is:
rehoboam
'a lot to drink' is the definition.
(Rehoboam is a large Champagne bottle)
'engineers tramp over a mile' is the wordplay.
'engineers' becomes 're' (Royal Engineers).
'tramp' becomes 'hobo' (synonyms).
'over' is a charade indicator (letters next to each other).
'mile' becomes 'm' (common abbreviation).
're'+'hobo'+'a'+'m'='REHOBOAM'
'as' acts as a link.
(Other definitions for rehoboam that I've seen before include "Son of Solomon: wine bottle six times larger than normal" , "Large champagne bottle" , "Very big wine-bottle" .)