Go on, chum! It’s of very little importance (6)
I believe the answer is:
paltry
'it's of very little importance' is the definition.
I can't judge whether this definition defines the answer.
'go on chum' is the wordplay.
'go' becomes 'try' (I've seen this before).
'on' says to put letters next to each other.
'chum' becomes 'pal' ('pal' can be a synonym of 'chum').
'try' put after 'pal' is 'PALTRY'.
Can you help me to learn more?
(Other definitions for paltry that I've seen before include "Feeble" , "Worthless and trifling" , "Worthless or trivial" , "Mean - worthless" , "Insignificant, trifling" .)