Game over with vacant mob about (5)
I believe the answer is:
ombre
'game' is the definition.
(I've seen this before)
'over with vacant mob about' is the wordplay.
'over with' becomes 'o' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'vacant' means to remove the middle letters.
'about' becomes 're' (common abbreviation for 'with reference to').
'mob' with its middle removed is 'mb'.
'o'+'mb'+'re'='OMBRE'
Can you help me to learn more?
(Other definitions for ombre that I've seen before include "solo player" , "Card game, the name derived from the Spanish for man" , "Tricky game" , "Shaded" , "- Stravinsky, composer" .)