Come down hard in a way that’s “petty”? (4,4,3,4)
I believe the answer is:
rain cats and dogs
'come down hard' is the definition.
(both can mean to rain heavily)
'in a way that's petty?' is the wordplay.
I cannot quite understand how this works, but
'in' is present in the answer.
'a' could be 'an' and 'an' is present in the answer.
'way' could be 's' (Compass direction - South) and 's' is located in the answer.
This explanation may well be incorrect...
(Other definitions for rain cats and dogs that I've seen before include "To fall heavily" , "Pelt" , "Pour" , "come down hard" , "bucket" .)