Runs to and fro in spacecraft, maybe, as it's being given once-over by mechanic (7,7)

'once-over by mechanic' is the definition.
I don't know anything about this answer so I cannot tell whether this works.

'runs to and fro in spacecraft maybe as it's being' is the wordplay.
I cannot really see how this works, but
'runs' could be 'r' (cricket abbreviation) and 'r' is present in the answer.
'to' could be 'shut' (I've seen this before) and 'shut' is found in the answer.
'it's' could be 'es' ('e' can mean 'electronic' which is similar to 'IT') and 'es' is found within the answer.
'being' could be 'levi' (Levi is an example) and 'levi' is present in the remaining letters.
This may be the basis of the clue (or it may be nonsense).

'given' acts as a link.

Can you help me to learn more?