Crossword Genius

Kelvin casual, playing horn (6)

Ross

I believe the answer is:

klaxon

'horn' is the definition.
(klaxon is a kind of horn)

'kelvin casual playing' is the wordplay.
'kelvin' becomes 'K' (abbreviation for the unit of temperature).
'casual' becomes 'lax' (I've seen this before).
'playing' becomes 'on'.
'k'+'lax'+'on'='KLAXON'

(Other definitions for klaxon that I've seen before include "Blaring horn" , "warning device" , "A kind of loud horn" , "Warning horn" , "Old car horn" .)

I've seen this clue in The Telegraph.
Want a hint initially instead of a full solution? Install my app