Study melting mess (9)
I believe the answer is:
confusion
'mess' is the definition.
(thesaurus)
'study melting' is the wordplay.
'study' becomes 'con' (con can informally mean to study).
'melting' becomes 'fusion' (melting or fusing things together).
'con'+'fusion'='CONFUSION'
(Other definitions for confusion that I've seen before include "Shame!" , "Bewilderment - disorder" , "Chaos" , "Uncertainty" , "Perplexity" .)