Very popular ruby stolen (3-3)
I believe the answer is:
red hot
'very popular' is the definition.
(I've seen this before)
'ruby stolen' is the wordplay.
'ruby' becomes 'red' (synonyms).
'stolen' becomes 'hot' (stolen goods are 'hot').
'red'+'hot'='RED-HOT'
(Other definitions for red hot that I've seen before include "Sexy" , "Very keen" , "Burning" , "Very busy" , "Strongly fancied to win" .)