triangle, for example (10)
I believe the answer is:
instrument
'triangle for example' is the definition.
(triangle is a kind of instrument)
This is the entire clue.
(Other definitions for instrument that I've seen before include "Means of precision work (or music-making)" , "legal document" , "Word puzzle" , "What's needed for 1 [MUSICIAN]" , "Joanna, perhaps" .)