Instruments we hear annoy ancient settlers (9)
I believe the answer is:
triangles
'instruments' is the definition.
(triangle is a kind of instrument)
'we hear annoy ancient settlers' is the wordplay.
'we hear' indicates a 'sounds like' (homophone) clue.
'annoy' becomes 'try' (I've seen this in another clue).
'ancient settlers' becomes 'angles' (I can't explain this - if you can you should give a lot more credence to this answer).
'try' sounds like 'tri'.
'tri'+'angles'='TRIANGLES'
Can you help me to learn more?
(Other definitions for triangles that I've seen before include "Geometrical figures" , "Three-sided shapes" , "Three-sided figures" , "Musical instruments" , "Three-sided polygons" .)