In cryptics, the generic describing the specific requires no indication, so in your example 'biped' as a definition (definition='a description of a thing according to its properties') of 'man' is fine.
It is the reverse that some people (myself included) consider an issue, eg 'man' as a "definition" of' biped', where 'man, for instance' or 'man?' would be appropriate. This is the 'definition by example'.
The 'name me a' test is a good guide for 'generics'. If I ask you to name me a biped, 'man' is a good answer. Likewise 'cod' would be good answer when asked to name a fish.
But when asked to name a man, 'Adam' would be ok but 'biped would not, and 'fish' wouldn't cut it if asked to name a cod.
For a more in-depth discussion, see my article:
http://www.thefrogman.net/index_files/Page716.htm