Suspicion understood by ruthless fictional species on being abandoned (7)
I believe the answer is:
inkling
'suspicion' is the definition.
(I've seen this before)
'understood by ruthless fictional species on being abandoned' is the wordplay.
'understood by' becomes 'in' (I can't justify this - if you can you should believe this answer much more).
'ruthless fictional species' becomes 'Klingon' (alien species in Star Trek).
'being abandoned' suggests deleting specific letters.
'klingon' with 'on' taken away is 'kling'.
'in'+'kling'='INKLING'
(Other definitions for inkling that I've seen before include "Clue" , "Vague notion" , "Vague idea" , "Faint notion" , "Glimmering of notion" .)