Paul's stout, kind of firm? (8)
I believe the answer is:
importer
'kind of firm?' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'paul's stout' is the wordplay.
'paul's' becomes 'I'm' (where the crossword setter is 'Paul').
'stout' becomes 'porter' (synonyms).
'im'+'porter'='IMPORTER'
Can you help me to learn more?
(Other definitions for importer that I've seen before include "Businessperson" , "One buys in" , "Foreign dealer" , "One who brings in" , "One bringing in goods to country" .)