Left aboard spaceship, Mike's worry reported to Houston? (7)
I believe the answer is:
problem
'worry reported to houston?' is the definition.
I can't judge whether this defines the answer.
'left aboard spaceship mike's' is the wordplay.
'left' becomes 'l' (common abbreviation).
'aboard' means one lot of letters goes inside another.
'spaceship' becomes 'probe' (I can't justify this - if you can you should believe this answer much more).
'mike' becomes 'M' (phonetic alphabet: alpha, bravo, charlie etc.).
'l' inserted within 'probe' is 'proble'.
'proble'+'m'='PROBLEM'
Can you help me to learn more?
(Other definitions for problem that I've seen before include "Matter hard to cope with" , "Snag" , "One hard to understand, solve" , "Something to be solved" , "Question or source of perplexity" .)