Strange clue - "Pair off"! (8)
I believe the answer is:
peculiar
'strange' is the definition.
('peculiar' can be a synonym of 'strange')
'clue pair off' is the wordplay.
'off' indicates anagramming the letters.
'clue'+'pair'='cluepair'
'cluepair' anagrammed gives 'PECULIAR'.
(Other definitions for peculiar that I've seen before include "I clear up, being odd" , "'Strange, odd (8)'" , "Unusual" , "Out of the ordinary" , "Odd, rum, funny" .)