Suspended old invader? Good! (4)
I believe the answer is:
hung
'suspended' is the definition.
(I've seen this before)
'old invader? good' is the wordplay.
'old invader?' becomes 'hun' (I've seen this before).
'good' becomes 'g' (abbreviation).
'hun'+'g'='HUNG'
(Other definitions for hung that I've seen before include "Dangled" , "(Of parliament) with no overall majority" , "Suspended" , "(Of a jury) unable to agree on a verdict" , "(Of a painting) exhibited (in a gallery)" .)