A drama involves the fleet (6)
I believe the answer is:
armada
'the fleet' is the definition.
(armada is a kind of fleet)
'a drama involves' is the wordplay.
'involves' indicates an anagram.
'drama' with letters rearranged gives 'rmada'.
'a'+'rmada'='ARMADA'
(Other definitions for armada that I've seen before include "A great fleet - Spain had one" , "Fighting unit" , "Fleet Drake defeated" , "Old Spanish fleet" , "Spanish fleet sent in 1588 to escort an invasion of England" .)