Thumping worker a bit (8)
I believe the answer is:
handsome
'thumping' is the definition.
(both can mean impressive)
'worker a bit' is the wordplay.
'worker' becomes 'hand' (hand is a kind of worker).
'a bit' becomes 'some' (I've seen this in another clue).
'hand'+'some'='HANDSOME'
(Other definitions for handsome that I've seen before include "beautiful" , "Fine-looking" , "Nomads he found to be good-looking" , "'Good-looking, as a man might be (8)'" , "Nice-looking" .)