Small problem on the internet? No great rush (6)
I believe the answer is:
stroll
'no great rush' is the definition.
(a stroll is a leisurely walk)
'small problem on the internet?' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'problem on the internet?' becomes 'troll' (annoying or provocative internet user).
's'+'troll'='STROLL'
(Other definitions for stroll that I've seen before include "Amble or ramble" , "A casual or lazy walk" , "Saunter in no particular direction" , "Meander" , "A quiet, pleasant walk" .)