Senior officer given bill covering case of gin and brandy (6)
I believe the answer is:
cognac
'brandy' is the definition.
(Cognac is an example)
'senior officer given bill covering case of gin' is the wordplay.
'senior officer' becomes 'co' (commanding officer).
'given' is a charade indicator (letters next to each other).
'bill' becomes 'ac'.
'covering' indicates putting letters inside.
'case of' means to remove the middle letters (outsides of).
'gin' with its middle removed is 'gn'.
'co'+'ac'='coac'
'coac' placed around 'gn' is 'COGNAC'.
'and' acts as a link.
(Other definitions for cognac that I've seen before include "warmer" , "Brandy as for Napoleon (6)." , "(French district famed for) fine brandy" , "Type of brandy" , "strong drink" .)