Crossword Genius

Old friend gets a stone (4)

Ross

I believe the answer is:

opal

'a stone' is the definition.
(gemstone)

'old friend' is the wordplay.
'old' becomes 'o' (abbreviation).
'friend' becomes 'pal' (pal can mean a friend).
'o'+'pal'='OPAL'

'gets' acts as a link.

(Other definitions for opal that I've seen before include "precious jewel" , "Type of gemstone" , "little jewel" , "Many-coloured gem" , "Milky-white gemstone with flashes of colour" .)

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