Stared at a spaceman (5)
I believe the answer is:
gaped
'stared' is the definition.
(I've seen this in another clue)
'at a space-man?' is the wordplay.
'at' is a charade indicator (letters next to each other).
'a space' becomes 'gap' (gap is a kind of space).
'man?' becomes 'Ed' (short for Edward).
'gap' next to 'ed' is 'GAPED'.
(Other definitions for gaped that I've seen before include "Opened mouth wide" , "Looked stunned" , "Stared open-mouthed - yawned" , "shown astonishment" , "Was yawning" .)