Peculiar or ha-ha? (5)
I believe the answer is:
funny
'peculiar or ha-ha?' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for funny that I've seen before include "Droll -- suspicious" , "Ha-ha or peculiar?" , "Amusing or peculiar" , "Comical" , "Strange; humorous" .)