Express them colloquially, and do by chance (6)
I believe the answer is:
embody
'express' is the definition.
(I've seen this before)
'them colloquially and do by chance' is the wordplay.
I cannot quite see how this works, but
'them' could be 'em' and 'em' is found within the answer.
The remaining letters 'body' is a valid word which might be clued in a way I don't understand.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for embody that I've seen before include "Incarnate or personify" , "Give solid form to" , "concretise" , "Express, say ideas, in visible form" , "Express concretely - personify" .)