Engineers to drink a French wine, gorge (6)
I believe the answer is:
ravine
'gorge' is the definition.
(thesaurus)
'engineers to drink a french wine' is the wordplay.
'engineers' becomes 're' (Royal Engineers).
'to drink' indicates putting letters inside.
'french wine' becomes 'vin' (I've seen this before).
'a'+'vin'='avin'
're' enclosing 'avin' is 'RAVINE'.
(Other definitions for ravine that I've seen before include "Deep narrow gorge between mountains" , "Defile" , "Deep narrow valley" , "Type of gorge" , "'Deep, steep valley (6)'" .)