Green’s Dictionary of Slang

1. (US) generic for a small-time trader, esp. in the stock market.

1951		S. Lewis World So Wide 186: They’ll make my ancestor Lorry the Magnificent, Serial One, look like a ribbon clerk.
1959		H.S. Thompson letter 25 June in Proud Highway (1997) 173: Loneliness and uncertainty are as common to artists [...] as they are to shit-shovelers and ribbon clerks.

2. (US gay) a gay man who has a desk job.

1956		J. Blake letter 21 March in Joint (1972) 78: Ribbon clerks they seem, prim and pallid.
1972		B. Rodgers Queens’ Vernacular.

3. (US gay) a heterosexual woman who prefers the company of gay men.

1999

Gaymart.com Queer Sl. in the Gay 90s 🌐 Ribbon Clerk – Another term for fag hag.