The most common and most likely answer to this crossword clue is the 6 plus 9 letter word DJANGO REINHARDT
I've seen this crossword clue in The Guardian
D
J
A
N
G
O
R
E
I
N
H
A
R
D
T
Buddy explains!
The straight part
We know that "Strummer" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case strummer = django reinhardt.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.