The most common and most likely answer to this crossword clue is the 8 letter word MERCHANT
I've seen this crossword clue in Independent
M
E
R
C
H
A
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T
More clues leading to the result MERCHANT
- French sea song required for commercial
- Season half gone — sing, as one doing business
- Dealer paid to maintain ranch building
- Nice sea song for fishmonger, perhaps
- Trader supposed to go round royal church
- Better economic growth finally welcomed by intended trader
- He sells car, the Chinese model
- Rock band coming back to sing in commercial
- One right out of Frenchman’s sea shanty?
- Commercial sea song?
Buddy explains!

The straight part
We know that "commercial" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case commercial = merchant.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does MERCHANT mean?
MERCHANT noun- A person who traffics in commodities for profit.
- The owner or operator of a retail business.
- A trading vessel; a merchantman.
- A supercargo.
- As a resident of a region, to buy goods from a non-resident and sell them to another non-resident.