Key member run out (6)
I believe the answer is:
legend
'key' is the definition.
(I've seen this before)
'member run out' is the wordplay.
'member' becomes 'leg' (member can mean a limb).
'run out' becomes 'end' (synonyms).
'leg'+'end'='LEGEND'
(Other definitions for legend that I've seen before include "famous player?" , "Superstar" , "Story from long ago" , "Traditional story - inscription" , "Story handed down from the past" .)