Green’s Dictionary of Slang

1. (US prison) a hiding place.

1977		E. Bunker Animal Factory 23: Stand point a minute, will you, Buzz? I went to check a clavo.
2000		Other Side of the Wall: Prisoner’s Dict. July 🌐 Clavo: A stash or collection. ‘He has a huge clavo of jelly-beans.’.
2005		Prison Slang Mommyblogger mydogharriet.blogspot.com 23 Sept. 🌐 So your shortie jacked some wham whams from her ace-duces clavo?

2. (US prison) a prisoner who is in possession of something valuable, esp. drugs.

1992

Bentley & Corbett Prison Sl. 52: Clavo Someone who is ‘holding the bag’ or the ‘dope sack.’ Can also be used to mean holding anything of value, i.e., money, jewels, etc.

3. (US campus) drugs.

1997

Da Bomb Summer Supplement 4: Clavo (n.) Spanish slang. Drugs.