It doesn't quite rate being petted (3)
I believe the answer is:
rat
'it doesn't quite rate being petted' is the definition.
The definition suggests a singular noun which matches the answer.
'it' is the wordplay.
I cannot quite see how this works, but
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is present in the answer.
The remaining letters 'ra' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for rat that I've seen before include "that gets out of stricken vessel" , "one who deserts the sinking ship?" , "Scumbag" , "one not going down with ship" , "Grass" .)