Continue, thug! (4)
I believe the answer is:
goon
'thug' is the definition.
(I know that thug can be written as goon)
'continue' is the wordplay.
I cannot quite understand how this works, but
'continue' could be 'on' (I've seen this in other clues) and 'on' is present in the answer.
The remaining letters 'go' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for goon that I've seen before include "Foolish person - thug (US)" , "He's very stupid" , "Sellers for example" , "Silly person - bully (US)" , "Hired thug" .)