Well, now at least I know of a way to move it around, but I have no
idea what the pair of numbers for x-extent mean (and #'(-5 . 5) puts
the clef in an even stranger place).
...
E.g. :
\version "2.20.0"
\paper {
line-width = 50
}
\layout {
indent = 0
system-count = 1
}
<<
\new Staff { R2.*4 c''8 8 8 8 8 8 }
\new Staff { R2. c''4 r r c'' r r r e'' r r d'' r }
\new Staff {
\clef F \time 3/4 R2.*3
\clef G g4 r r g r r
\once\override Staff.Clef.X-extent = #'(-2 . 0)
%\once\override Staff.Clef.space-alist = #'((staff-bar extra-space . 5))
%% or:
\once\override Staff.Clef.space-alist = #'((staff-bar minimum-space . 2.2))
\clef F
}
>>
HTH
Cheers,
Pierre