Observe phantom, about to move forwards (7)
I believe the answer is:
respect
'observe' is the definition.
(as in observing or respecting rules)
'phantom about to move forwards' is the wordplay.
I cannot quite understand how this works, but
'about' could be 're' ('re' means regarding or about) and 're' is present in the answer.
This explanation may well be incorrect...
(Other definitions for respect that I've seen before include "Have high regard for sceptre" , "Due regard; admiration" , "Appreciation" , "'Regard, esteem (7)'" , "Show honour to" .)