Nip backwards and forwards serving fizzy drink (3)
I believe the answer is:
pop
'fizzy drink' is the definition.
(pop is a type of fizzy drink)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for pop that I've seen before include "Sound of a balloon bursting" , "Old jingle - . . . goes the weasel" , "Burst - fizzy drink - modern music - US dad" , "Palindrome of music for the young" , "Music with mass appeal" .)