Strange characteristic (8)
I believe the answer is:
peculiar
I believe this clue is a double definition.
'strange' is the first definition.
(synonyms)
'characteristic' is the second definition.
(I've seen this before)
(Other definitions for peculiar that I've seen before include "I clear up, being odd" , "Odd, rum, funny" , "'Strange, odd (8)'" , "sick" , "Strange, I clear up" .)