Funny games with copper, one you can't trust (8)
I believe the answer is:
peculiar
'funny' is the definition.
(I know that funny can be written as peculiar)
'games with copper one you can't trust' is the wordplay.
'games' becomes 'pe' (abbreviation for Physical Education).
'with' is a charade indicator (letters next to each other).
'copper' becomes 'Cu' (Cu is the chemical symbol for copper).
'one you can't trust' becomes 'liar' (dishonest person).
'pe'+'cu'+'liar'='PECULIAR'
(Other definitions for peculiar that I've seen before include "Strange, different from the norm" , "Out of the ordinary" , "Odd - individual" , "Strange or eccentric, quite odd" , "I clear up, being odd" .)