Passing star in ground with politician (10)
I believe the answer is:
transitory
'passing' is the definition.
(I've seen this before)
'star in ground with politician' is the wordplay.
'ground' is an anagram indicator (grind the letters ).
'with' means one lot of letters go next to another.
'politician' becomes 'tory' (I've seen this before**).
'star'+'in'='starin'
'starin' anagrammed gives 'transi'.
'transi'+'tory'='TRANSITORY'
(Other definitions for transitory that I've seen before include "Passing" , "Here-today-gone-tomorrow" , "Fleeting" , "Ephemeral" , "Brief" .)