It’s pouring rain and cooler (4)
I believe the answer is:
stir
'cooler' is the definition.
(both are slang terms for prison)
'it's pouring rain' is the wordplay.
I cannot quite understand how this works, but
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is present in the answer.
The remaining letters 'sir' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'and' acts as a link.
Can you help me to learn more?
(Other definitions for stir that I've seen before include "Whisk or rotate" , "Slight movement" , "Rotate spoon" , "created by an agitator?" , "Agitate - disturbance" .)