The Collaborative International Dictionary
Claggy
Claggy \Clag"gy\, a. [Cf. Clog.] Adhesive; -- said of a roof in a mine to which coal clings.
Wiktionary
claggy
a. 1 (context of mud, tar, glue or the like English) Sticky or tacky. 2 (context specifically, of a roof in a mine English) adhesive, having coal clinging to it.
Usage examples of "claggy".
I think, from maize flour taken from an Oxfam sack and a cloggy, claggy concoction, brick red in colour, which tasted both yoghurty and metallic.