diff --git a/src/parser/clock.rs b/src/parser/clock.rs
index a3d94c8..5b71e01 100644
--- a/src/parser/clock.rs
+++ b/src/parser/clock.rs
@@ -1,8 +1,44 @@
+use nom::branch::alt;
+use nom::bytes::complete::tag_no_case;
+use nom::character::complete::space0;
+use nom::character::complete::space1;
+
 use super::Context;
 use crate::error::Res;
+use crate::parser::parser_with_context::parser_with_context;
+use crate::parser::util::get_consumed;
+use crate::parser::util::maybe_consume_trailing_whitespace_if_not_exiting;
+use crate::parser::util::start_of_line;
 use crate::parser::Clock;
 
 #[tracing::instrument(ret, level = "debug")]
 pub fn clock<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, Clock<'s>> {
+    start_of_line(context, input)?;
+    let (remaining, _leading_whitespace) = space0(input)?;
+    let (remaining, _clock) = tag_no_case("clock:")(remaining)?;
+    let (remaining, _gap_whitespace) = space1(remaining)?;
+
+    let (remaining, _timestamp_junk) = alt((
+        parser_with_context!(inactive_timestamp_range_duration)(context),
+        parser_with_context!(inactive_timestamp)(context),
+    ))(remaining)?;
+
+    let (remaining, _trailing_ws) =
+        maybe_consume_trailing_whitespace_if_not_exiting(context, remaining)?;
+
+    let source = get_consumed(input, remaining);
+    Ok((remaining, Clock { source }))
+}
+
+#[tracing::instrument(ret, level = "debug")]
+fn inactive_timestamp_range_duration<'r, 's>(
+    context: Context<'r, 's>,
+    input: &'s str,
+) -> Res<&'s str, &'s str> {
+    todo!()
+}
+
+#[tracing::instrument(ret, level = "debug")]
+fn inactive_timestamp<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, &'s str> {
     todo!()
 }