Bust of a meth lab is understandable (10)
I believe the answer is:
fathomable
'understandable' is the definition.
(I've seen this before)
'bust of a meth lab' is the wordplay.
'bust' indicates anagramming the letters.
'of'+'a'+'meth'+'lab'='ofamethlab'
'ofamethlab' is an anagram of 'FATHOMABLE'.
'is' is the link.
(Other definitions for fathomable that I've seen before include "Comprehensible" , "understandable" .)