fossick for likely customer crossword clue

 The answer to the cryptic crossword clue "fossick for likely customer" is PROSPECT.

The wordplay clue in this clue is the word "fossick." Fossick is a verb that means to search for something, especially for gold or other minerals. In this clue, the word "fossick" is being used as a homophone for the word "prospect." A prospect is a potential customer.

The answer to the clue is also supported by the definition clue. The definition of "prospect" is "a potential customer."

I hope this helps!