Mark and the others lead? (5)
I believe the answer is:
metal
'lead?' is the definition.
(lead is a metal)
'mark and the others' is the wordplay.
'mark' becomes 'm'.
'and the others' becomes 'et al'.
'm'+'etal'='METAL'
(Other definitions for metal that I've seen before include "Given lead, perhaps" , "Zirconium, for example" , "Material detectable in the ground" , "Tungsten, for example" , "lead as one" .)