Second salesman is portly (5)
I believe the answer is:
stout
'is portly' is the definition.
(synonyms)
'second salesman' is the wordplay.
I cannot really understand how this works, but
'second' could be 's' (common abbreviation) and 's' is located in the answer.
The remaining letters 'tout' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for stout that I've seen before include "Round" , "Heavily built; drink" , "pint" , "Dark beer for the rather fat" , "Beer with malt" .)