Pass time surrounded by swirling aurora - lots of decorative stuff here (10)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

COL (a mountain pass between two peaks), then T (abbreviation for time) surrounded by an anagram (swirling) of AURORA . Musical term for a melody sung by a soloist (usually soprano) with lots of ornamentation: trills, runs of fast notes, and/or generally showing off.