Bizarre exercise with perjurer protecting copper (8)
I believe the answer is:
peculiar
'bizarre' is the definition.
(thesaurus)
'exercise with perjurer protecting copper' is the wordplay.
'exercise' becomes 'pe' (Physical Education).
'with' is a charade indicator (letters next to each other).
'perjurer' becomes 'liar' (a perjurer lies in court).
'protecting' is an insertion indicator (inserted letters are held or protected).
'copper' becomes 'cu' (chemical symbol).
'pe'+'liar'='peliar'
'peliar' enclosing 'cu' is 'PECULIAR'.
(Other definitions for peculiar that I've seen before include "sick" , "Characteristic" , "'Curious, odd (8)'" , "Strange or eccentric, quite odd" , "Odd - individual" .)