### Clue: Matter in the main well liquefied? (9)
### Answer: MELTWATER 
 ### Explanation: Definition: Matter in the main well liquefied?

***(matter wel)** [anag:*liquefied*] where WEL is WEL(l) [*in the main*] and &lit.
 
*Chambers has MELT-WATER hyphenated.