The most common and most likely answer to this crossword clue is the 6 plus 3 plus 4 plus 2 plus 6 letter word ANSWER THE CALL OF NATURE
I've seen this crossword clue in The Guardian
A
N
S
W
E
R
T
H
E
C
A
L
L
O
F
N
A
T
U
R
E
Buddy explains!
The straight part
We know that "Go/howl back?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case go/howl back? = answer the call of nature.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.