Ghost is a little suspect, really (7)
I believe the answer is:
spectre
'ghost' is the definition.
(synonyms)
'a little suspect really' is the wordplay.
'a little' indicates a hidden word.
'SPECTRE' is hidden in the letters of 'suspect really'.
'is' is the link.
(Other definitions for spectre that I've seen before include "Wraith" , "Narrow ravine" , "Enemy organisation for James Bond; ghost" , "spirit" , "something seen as a threat" .)