### Clue: Unfinished clue I'm altering, about utopian's head in clouds (6)
### Answer: CUMULI 
 ### Explanation: Definition: clouds
An envelope ('about') of U ('**U**topian's head') in CMULI (or …), an anagram ('altering') of 'clu[e]' minus its last letter ('unfinished') plus 'I'm'.