Assessment of family caught in possession (8)
I believe the answer is:
thinking
'assessment' is the definition.
(thesaurus)
'family caught in possession' is the wordplay.
'family' becomes 'kin' ('kin' can be a synonym of 'family').
'caught in' indicates putting letters inside.
'possession' becomes 'thing' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'kin' going within 'thing' is 'THINKING'.
'of' acts as a link.
Can you help me to learn more?
(Other definitions for thinking that I've seen before include "Take" , "rationale" , "Pondering" , "Considering in the mind" , "consideration" .)