Boring drone acquires some timpani (7)
I believe the answer is:
humdrum
'boring' is the definition.
(I've seen this in another clue)
'drone acquires some timpani' is the wordplay.
'drone' becomes 'hum' (drone can mean to make a humming sound).
'acquires' means one lot of letters go next to another.
'some timpani' becomes 'drum' (I've seen this in another clue).
'hum'+'drum'='HUMDRUM'
(Other definitions for humdrum that I've seen before include "Run-of-the-mill" , "Everyday, tedious" , "Droning sounds" , "Dull (of existence)" , "Commonplace, dull" .)