The clip is just to hold the ABS and brake wear sensor cables. The oil means that strut is dead and needs replacing. It's not a hard job, but make sure you brace the control arm and are prepared for some fun breaking the top nut loose.
There's a great writeup in the DIY section of this very website.

__________________
RIP:
2011 E350 BlueTEC, Schwartz 81k (totaled by uninsured drunk driver)
1964 Unimog 404.1 (wrongfully towed by the city)
1994 E320, Brilliantsilber 208k (transmission shuffled off after sudden catastrophic fluid loss)
1982 300D, Silberblau under a blue repaint 256k (sold for parts)
1995 E320 Polarweiss, 131k (sold for parts)
1995 E300D Polarweiss, 287k (totaled by drunk driver)