Clue: Dreadful lecher, sacked by new vice-chancellor, is emotionally unstable (8)
Answer: VOLCANIC
Explanation: Definition: emotionally unstable
I couldn't parse this, but KVa in the comments gave me the parsing (see comment 1) 
*(lecher) [anag: *dreadful*] removed from [*sacked by*] *(vice chancellor) leaves the letters you need to get an angram of **VOLCANIC