Found:
free relative
SYNTAX: relative clause that occurs without an antecedent. EXAMPLE: the subject in (i), who finishes first, is a free relative.
(i) [who finishes first] wins the prizeUsually one assumes that free relatives are NPs with an empty head noun: [NP 0 [S who finishes first]].
| LIT. | Smits, R.J.C. (1989) |