Green’s Dictionary of Slang

(US gay) an effeminate male homosexual.

1972		B. Rodgers Queens’ Vernacular 72: effie (dated, hetero sl, ’30s, fr L effeminatus = an effeminate boy) stereotype effeminate homosexual.
1989		B. Simon ‘Score Me the Ages’ Born in the RSA (1997) 171: Some fucken little queen wants to invest in me. [...] It’s okay, everything’s safe. I always use effies.
1997		J.M. Coetzee Boyhood (1998) 57: He shuts his mind to the backside-words in distaste but continues to try and puzzle out the meaning of effies and FLs.