Are nitrates changing brewing equipment? (3,8)
I believe the answer is:
tea strainer
'brewing equipment?' is the definition.
'are nitrates changing' is the wordplay.
'changing' indicates an anagram.
'are'+'nitrates'='arenitrates'
'arenitrates' is an anagram of 'TEA-STRAINER'.
(Other definitions for tea strainer that I've seen before include "It catches falling leaves" , "full of holes" , "What is to collect leaves" .)